I build 10/22's on a regular basis. 10/22's payed for a new mustang and a new ranger... I've done a few of 'em.
The biggest mistake people make is buying all sorts of fancy and expensive parts, yet forget about the most important stuff; the scope mount and scope.
Get a nice one piece base, rings and a good scope. (Dont be tempted to skimp) Millet and Bushnell both make a great scope for not a lot of cash. Of course, the sky is the limit.
Rebarrel; Green Mountain, Tactical Solutions and the lowly Butler Creeks are my favorites. Barrel changes are easy, just make sure you tighten the two bolts in the block evenly. And use quality ammo. For plinking and hunting, I prefer Green Tags. There are more expensive options, but I've found that the green tags have a nice balance of power and precision; and they are easy to find. Stay away from the hyper velocity rounds such as the Stingers. You do loose a good bit of accuracy with them.
Stocks; there are a lot of good options. Fancy custom laminates to the Hogue overmolds. Personally, I like the Hogues. My 10/22 "Sixto's Squirrel Special" sports the Hogue, its a great stock that is tough as nails. Perfect for hunting IMO. (the "squirrel special" has a Butler Creek .920 a one piece scope mount, Hogue stock... less than $200 in aftermarket parts, it will bust TicTacs at 30 yds easily if you do your part.)
Trigger groups; You can do a lot with the stock trigger, you may want to monkey around with it a little prior to spending a lot of cash on a new trigger group. There are a few good ones out there, but IMO, the best is still the Volquartsen. Its pricey, but its good stuff.