You can get an M1 through Civillian Marksmanship Program www.odcmp.com
You need to jump through a few hoops to get it, but inmho its the only way to get a good M1 at a decent price. I paid a shade over $500 for my HRA service grade rifle, its accurate and in great condition- I highly reccomend them. You could go the gunshow/pawn shop route and pay $700-1000+ for an M1 but unless you have the tools to guage the barrel wear, and are knowledgeble about the mechanics of the rifle, its a crapshoot and you could get burned.

BTW: stay away from garands with 'Century" receivers. They are much cheaper than a US model Garand, but they are junk.