On the contrary, I think it has significant potential. My reasons:
1) .biz makes you stand out as a business. Your visitors get to know that immediately, and I have a feeling .biz will get a slow but sure gathering of followers.
2) Your visitors know exactly what the site does: it allows you to compare prices. What of, I don't know, but think of what potential it has if you use something like Ajax and do a drag and drop of two items you find online. Do a search, drop one in one column, do another search, drop it into the second. Show a list of stores carrying the item, maybe rate the stores and the item itself too, and you have a winner.