I did a search for iPad and then sorted by price. This produced lots of irrelevant results such as handbags and headphones.

Not sure how your script calculates relevance, but perhaps the search term appearing in the title would be a better indicator of relevance.

Also I like the fact that when you click the 'more details' link it does a more focused product search. However, naming the link 'more details' suggests, to me anyway, that I will be taken to a page with more info on that specific product. Perhaps renaming the link to something like "similar products" would make for a more intuitive function.

Good job with the site, by the way, and good luck.