Parts are widely available, in fact CMP can get you pretty much any part you need.

Barrels- Krieger makes two types of barrels for the M1, one is of GI profile and is reasonably priced, the other is a match barrel.

Another place to buy a Garand and parts from, though it'll cost more than CMP is here:
http://www.garandguy.com/

Fulton armory and Dean's gun restoration both service and rebuild M1s and carry parts.