I just ran across this Google sub-service called Froogle (I thought that was kind of clever ).

Anyway, it already found me a price that didn't show up on any other price search sites. I found the Sony Ericsson P800 for $499 with activation. Pricegrabber, MySimon, and all the others showed nothing like this, and not even half of the total results.

Try it out. I'll be using it instead of Pricegrabber from now on.

more info

ps-I bought the phone as a direct result of the price find