Welcome aboard.
OK, $1,000... Good start! What do you want it to do? Target? Hunting? Self-defense? General Purpose?
If you aren't interested in hunting in which you are going to need a longer barrel to enhnace accuracy I would go with a flat-top carbine with a A2 front sight and a detachable carry handle. Down the road you could remove the carry handle and mount a back-up iron sight like the Arms 40 along with an optic like an Aimpoint, Eotech, Reflex or Acog.
But for now, lets focus on a postban rifle and the accessories you are going to need.
Do you want to buy a complete rifle or do you want to build it from parts and save some money? I personally would built it and learn the rifle. There are plenty of guys in Texas who could help you get started.
I would order one of the Century arms receivers from Wholesale Guns and Ammo on LI, NY for $89.99 plus shipping and transfer. Final cost will likely be $125 or less. Now in general you will hear to avoid Century products, some are good some are garbage. I can tell you that there AR15 lower receiver is forged and made in the same factory as Colt. They are a steal! I've seen them and would not hesitate to buy one.
I would then order a good Rock River Arms or JT Distributing post-ban carbine kit. Pete in NH (Legal Transfers) has great prices on RRA. JT is also well respected. There are other companies you can get kits from as well, they include Sherluk, Model 1, M&A. I would avoid American Spirit Arms, seem to be a lot of complaints about them.
You will have options when you order a kit.
Chrome lined barrel - worth the extra $50
Muzzlebrake - not needed on a .223/5.56
Stock - go with the A2 rather then the fixed post-ban collapsible
5.56 or .223 - get the 5.56, you can shoot .223 through a 5.56, but not vice versa
Now the reason I suggest you get an A2 stock instead of the fake collapsible stock is it is sturdier and if you decide to buy a second upper, say 20 or 24 inch heavy barrel for target or hunting, you then have the better stock in place for that purpose, and you just use the same lower.
So, $125 for the receiver shipped and transferred.
Carbine kit with detachable handle from JT, @525shipped
10 SA80 magazines from Ronin45, $150 shipped
Detachable carry handle
$200 case of 5.56 ammo
Anyway, that's how I'd get started.
Edited to add:
JT Distributing
[url]http://webcats.net/store/merchant.mv?Screen=PROD&Store_Code=J&Product_Code=C1C&Category_Code=K[/url]
Wholesale Guns and Ammo 631-208-9500