there are a number of sites you can look. here is a few site I have ordered sks parts from as well I have looked at. I mainly seen bull pup and m4 looks.

http://www.tapco.com/proddesc.aspx?Id=ff5fb45e-667e-4d52-a464-527196389cbd

http://www.sksman.com/acces/ruger10_22.php

http://www.cheaperthandirt.com/1022_jhc.htm

http://www.lockstock.com/

the first 2 sites I have dealed with both have good CS. the second is a small compeny, chances you will deal with the owner.
the third I have not order anything from but I have thought about it.
the forth I just got an ad from and just added for the hell of it.