Now that you have 2 lowers (good call) I'll add my 2 cents:
Mags. This will be one of the first bans they try to ram down our throats. Get some 20 and 30 round aluminum mags from NHMTG/Okay. How many is up to you, but 5 of each would be a good start. These are the best USGI mags out there.
While you are researching what you want to build, start getting some of the common parts that are used in any 5.56 AR, such as the pistol grip, the lower parts kit, and a quality HPT/MPI bolt carrier group. As you accumulate this, you can decide what kind of barrel, handguard or free float rail, sights, buttstock and carbine or rifle buffer system you want.
As you are doing this, keep an eye out for ammo deals, cause prices will go up and availability will go down as we get closer to election time. And write a friendly letter to your representatives stating how you value your rights, including the 2A.