Try this one. All the CSP forums are pretty good.
http://www.jouster.com/cgi-bin/garand/garand.pl
Values of the M1 Garand are a bit suppressed right now due to the flood of them from the CMP and all those re-imported into this country from other countries. The most valuable are the pre WW2 manufactured ones and WW2 rifles made by Winchester tend to have good value
Greg