Metaebooks,
Nice looking site. You should strongly consider reaching out to these retailers before screen scraping their content.
I would prefer you use a datafeed from us. Contact me through our customer support system and I'll help you out.
This way you can make sure to update prices frequently and also make sure you capture the site appropriately. We have a different structure than most as we try to have "one price" for as many titles as possible. Again, this is a recent change.
I look forward to working with you and congrats on your site!
Clint Brauer
www.cyberread.com