Comparison shopping site database population

[photografica]

Hey All.. I'm new to the site, I thought I would ask some questions here since it looks like this is the place with all the answers :>

What I am trying to do is develop a smaller shopping comparison site where vendors can submit their data feed to be listed with other vendors products, and compete for the lowest price.

Where im running into problems is, how would I gather all the information for the original database, like features, specifications, description and photos, without doing it manually of course. Does anyone have any ideas or suggestions on this?

Thanks,
Frank