Curio and Relic Dealers Curio and Relic Firearms Collecting and Shooting the Military Surplus Rifle (2006) - Surplusrifle.com
These are a good start..
I typically purchase from SOG, AIM, and Century, and also find several on Gunbroker and AuctionArms..
I like SOG and AIM because the shipping is fast and pretty cheap with them just being north of Cincinnati. Even moreso when it comes to ammo just because they're close to me (and you) and the shipping's less.