Well I think the problem with auto programs are that merchandise companies can code their sites or directories in such ways as to fool most auto entry programs and get their products better ratings and listings.
on the other hand, if you do it manually you'll need someone trusted to review each pricelist entered to make sure it's not just random numbers and products entered by someone wanting to make "a quick buck".
To counter this u can always design some "loyalty" system to award dedicated users who puts some effort into providing best information.
Overall it sounds like a damn interesting idea. I'll be more than happy to help you Ben.Maybe be your first "product lister".
