First off, I wouldn't buy anything other than one built on a GI receiver (Winchester, IHC, H&R, or Springfield, and that's NOT the Springfield Armory/Geneseo Ill.) Since you're not worrying about a "correct" M1 (with matching/period correct drawing numbers/mfg markings) any GI receivered Garand ought to be good to go. Replacement barrels are releatively cheap and plentiful, as are virtually any other part you may need. Likewise, don't get suckered into buying an "all original, correct" M1 garand.

True, "all original", undinked Garands are as scarce as chicken lips. Virtually all Garands under went at least one rebuild in their government service life. GI armorers generally didn't pay too much attention to making sure drawing numbers and mfg markings matched. They were more concerned with building a functional, accurate, and reliable service rifle.

As to rewelded garand receivers, you shouldn't worry too much, provided the receiver was rewelded by someone knowledgable in Garands and rewelded it to spec'd dimensions (and rewelded it correctly.) Still, if you're suspect of reweded receivers, you shouldn't have too much trouble spotting a rewelded receiver provided you can make a close examination of the receiver off of the stock. FWIW, Fulton Armory also has a pretty good write up about rewelded Garands at: www.fulton-armory.com/Weld.htm

The current offerings by Century Arms and those built on the Lithgow receivers are iffy at best. I've played with/shot two non-GI M1 Garands and both had serious quality problems. On one, the op rod kept jumping track, the other had too much slop in the action, op rod, and gas nut. Neither would hold a decent group. If my word on teh non-GI Garands isn't good enough, go to Fulton Armory's web page and read their reviews of them.

Fulton Armory's write of the Century Arms Garand:
www.fulton-armory.com/CAI-TI.htm
Fulton Armory's write of the Lithgow receivered Garands:
www.fulton-armory.com/Lithgow-TI.htm