Regarding Sparks, I can only echo T Bones points. If you want a Sparks, you wait and pay. If you don't want to wait, you can always check out eBay and pay an outrageous markup from the price gougers that are the reason there's a wait time.
There are other makers, but IMHO Milt Sparks is one of the best, the others having even more of a wait. OR you can try to order the Sparks from
Lightning Arms Sports, at a higher price...
For similar IWB styles if you don't want the Sparks, I'd go with the above mentioned guys, UBG, HBE, TT Gunleather, FIST, and Desibens Gun Leather now that Rhome is back in the states. I was just checking out his
website and I can't wait to get me one of the #2 IWB holsters...
Now that's a nice looking rig.
I've dealt with all of the above mentioned makers except FIST, but I've never heard a complaint about them.