I am currently using Google Base feeds with my website but am interested in possibly looking at comparision shopping sites such as Nexttag, Shopzilla, Shopping.com, Bizrate, Yahoo Shopping, MSN Shopping, Pricegrabber, and Pricescan.
It seems like most of these are cost per click services. Are there any that you only pay when someone purchases? I have no clue how many clicks we'd get but I have concerns of getting a high bill from a lot of clicks from people with no intent to purchase. Also, we sell electronics such as computers and accessories, a/v accessories and video games and am wondering which comparison site would work best for the type of business we have.
Thank you for assistance.

Most of those sites have a free $50 code or something..(so you can test the market) they are only as good as you throw money at them.. for some they are great, others.. a waste of money

If you can not compete by price, I would avoid them.. as that is what most people on those sites search for.. price and price/shipping