My first stop when I am in the mood for comparison shopping is Yahoo's shopping page. They have a huge selection of stores and a good rating system. But when I went today looking for ink cartridges I noticed something that renders Yahoo Shopping completely useless – it no longer appears to be possible to order search results by price. You can 'refine' your search by price and essentially implement your own bounds search but that is a huge waste of my time. They actually crippled their own site! I hate it when a good site goes stupid. I guess I'll have to us my backup sites.
My backup site, http://www.kelkoo.com/, is now a “Yahoo! company”, apparently – http://docs.yahoo.com/docs/pr/release1160.html
You can “compare prices” on some items, and sort by price, e.g. http://digitalcameras.kelkoo.co.uk/ctl/do/sort?pid=13444152&catId=124901&tsSearchId=1149886797617&searchId=1010201_1149886797617_330260654&field=totalprice&sortcolumnid=total_price