Do you have a Curios and Relic FFL?
You fill out some paperwork you get from the ATF send in your $35. 00 for 3 yrs. , then you can directly order firearms that are on the C&R list or are at least 50 yrs. old. You can order from firms like AIM Surplus, Empire Arms, SARCO, Century Arms, Wholesale Guns & Ammo and vendors on Gunsamerica, Gunbroker, and Auction Arms. If you belong to a CMP affiliated Gun Club you can even order rifles from the Civilian Marksmanship Program.
If you're only interested in current manufacture firearms nevermind. But it'll also get you dealer prices from Midway and Brownells that can pay for the license in a jiffy. I just purchased two rifles from a guy that advertised on the for sale section in thehighroad.org. WWII issued Garand and a Springfield 03A3, they were in great condition and delivered right to my PO.