So, you're looking for advice on your first AR...
I've lost track of the number of threads I have seen on this issue, and I seem to see the same responses every time, and I post the same thing every time.
If you are just looking for an AR because of the political climate, or once a month go dump a few mags at pop cans and dirt clods, stop reading now and go buy what ever the heck you want.
If you are seriously looking into this platform and are willing to do your part, and want something that will last, keep reading.
To start with, you are on the wrong forum. This forum is primarily a handgun related, and activities revolving around that platform. I strongly recommend going to M4carbine.net and spend a great deal of time reading and using the search feature. If the question has been asked, or the argument held, it's in there.
First and foremost: Do your homework BEFORE you buy! [Thank you atctimmy] which pretty much translates into "Buy once, cry once."
Second: Budget. You saved up $1000 for a rifle. I have some bad news for you. You don't have enough money. Sure you can go out and buy some well known cheap rifle for $600 - $800 (RRA, Stag, Bushmaster [or any of their spin offs], CMMG, DPMS) but if you think you got a smokin' deal, you didn't. You will spend another $200+ to fix known problems with them or replace parts that are of crap quality. "The Chart" that was originally compiled by Rob S. is no longer available. This is an unfortunate turn of events, and somewhere out there someone had the foresight to make a copy of it before it was removed from Tactical Yellow Adviser, and hopefully it will turn up in the other sticky thread here. To sum it up, it clearly details a large variety of manufacturers and their rifles, what they are made of, what tests were done to key components, and what specs they meet - if any.
I'll simplify this for you. Colt, BCM, & PSA are your current top choices for an entry level rifle that is of quality, and those start at $900. This is not some "Name Brand" snobbery, this is not my opinion, this the truth. Colt has the Technical Data Package for the military's M4, BCM has done a stellar job at matching the specs, and has a proven track record to back it up, and finally PSA is up and coming, and thus far is among the top dogs in the quality and reliability race for the money spent. That is the key point. Dollar for Dollar, those three are going to get you the best quality, and reliability for the money. Both of my assemblies are bits and pieces of BCM, PSA, Vltor, Centurion, Magpul, and Midwest Industries. No snobbery here, I don't own an off the rack rifle, and never will. That's just me.
"Why don't I have enough money?"
Incidentals that people just don't think about. When you buy the rifle, that is all you got. A basic rifle and 1-3 mags. No ammo to shoot, no RDS (Red Dot Sight - not mandatory, but trust me, you will want one), no sling, no additional mags (generally 5-10 is what you want on hand ~ I'll get into that later), no weapon light (especially if you want this rifle for any personal defense reasons - another point to get a proven quality rifle).
There are only 2 or 3 manufacturers out there that make the basic accessories listed, and again, do your homework and buy quality. DON'T SKIMP! For just those 5 listed - that's $850 for an Aimpoint PRO (cheapest and best quality RDS), 500 rounds of factory 5.56 ammo, 8 Pmags, a good 2 point sling, and a weapon light. If you shop around you may save $200 - $300 by catching sales or buying used off the equipment exchange on various forums. If you go to Ebay, make damn sure that it is the actual brand name, not an Asian knock off.
"WOW! I only wanted to spend $1k and go shooting and now I am up to $1800 and I haven't even pulled the trigger yet! What can I do to save a little cash?"
Buying parts to assemble: Again, Do your homework BEFORE you buy!. Yes you can assemble a lower (if you have the skills and tools) cheaper than a complete, but it is near impossible to assemble an upper from parts cheaper than buying one outright. There are specific tools that you will need to do an assembly, and those cost money - you have to figure that in. Brownells has a series of videos on AR assembly and are spot on.
Benefits to assembling over buying complete: You get to pick and choose the exact parts that you want. Trigger (FCG), Bolt carrier group (BCG), Lower parts kit (LPK), Receiver extension style, Handguard or quad rail, Back Up Iron Sights (BUIS), barrel length and twist rate, muzzle device.... Most places allow you to custom build your rifle with options, but they may not be the ones you want or need. Buying a basic entry level means that you will likely be replacing things down the road like the stock, FCG, BUIS, handguard or rail...Now you have a pile of parts in a box collecting dust.
Skill: If you are the type of person that takes their vehicle to the shop for anything and everything, assembling a rifle is probably out of your skill set and you should avoid trying.
"I can't fund this kind of project."
No biggie. Start with the basics and pick up the strays as you go. Another option if you can swing $25 a week is to get a signature loan from your bank for $1k to finish your funding. Make a $25 payment each week (real easy with direct deposit and online banking) and this will reduce the amount of interest you accrue each month. Still $100 a month payment but you are paying your loan off faster. Double bonus - if you make all the payments, you up your credit rating. I've done it 5 times myself.
"OK, I took your advice spent twice as much as I planned you jackwagon, now what?"
Go to a range and get your rifle sighted in, and get the feel for it. Don't just fling ammo down range. Fire a mag (or less), then check your target to see how you are doing. An AR in the hands of someone with rudimentary skills and irons should be able to hold a 16" group at 100y and 4" at 25. Don't burn through all your ammo. 100 rounds should be sufficient for the first trip. Pack up your toys and go home to clean your rifle (not necessary, but you should do this to learn how).
Time to go take a class. Appleseed for first time rifle shooters. You will learn tons. Now keep your eye out for an entry level carbine course. Here is where you want all the extra mags. Most entry level classes will be a 1 or 2 day session, and you will need 500 - 1k rounds of ammo (Uh Oh - there goes another $500 - $1k if it's close enough for you to commute from your home). You do not want to be That Guy holding up the class because you only have 3 mags and are constantly having to step off the line to reload. Hint - stripper clips are your friend! Read this thread about taking a training class This is a must read, and you will find yourself spending another $250+ on gear.
"OK I read this long arse post, and I think you are an arrogant know it all and FOS."
That may be. My first AR was assembled in Dec 2011 (do a search, there is a thread here on it). I just finished my second assembly last month, that one is $1900, and going to leap into the low $3k when I buy my scope (thread on that one too). My first one started out with a budget of $1800 - no ammo. I asked questions, I received advice from well respected members here, I did my research, and a month and a half later I started buying. By the time it was all said and done, I was $2700 into the project, and most of that was on sale. 3 months later I took the opportunity to take an advanced carbine course that was being held locally. I learned a great deal of the capabilities of my rifle, the reassurance that I made the correct choice in components that I bought. 30 days later there was another course and I took that too. 2400 rounds down range in one month and no failures. I have invested $1600 alone into learning about the platform and how to operate it. I am still nowhere near operator status with a lowly 7k rounds down range and 3 carbine classes in 1 year. I did however see weapons and optics fail, and they were not Colt, BCM, PSA rifles, or Aimpoint or Eotech optics.