I researched this a few months ago (this will get me to look again). I understand that
Commission Junction is the one the big boys like ebay use.
I was also pointed to
this guy as the guru and he seems to have ideas for different strategies whether you are buying and/or selling, etc. Seems he could answer your specific questions.
Note: seems "commission fraud" comes up as a concern alot so someone like Commission Junction, linkshare.com, clickbank.com... might be a good bet for my $0.02.
I hope this helps!