Sue, Signman (and anyone else interested),
If you regularly purchase from Priceline, you actually CAN DO BETTER. You can also get cash back on your $55 purchase.
I don't know if you are familiar with these sites, but both are reputable.
Fat Wallet offers 3% back on PL bookings: http://www.fatwallet.com/stores.php?catid=20
eBates also offers a rebate. They say that they offer $3 per hotel booking. http://www.ebates.com/stores_category.go?navigation_id=10001&category_id=54
Both offer other rebates through other web sites, too.
This is not a scheme. Companies pay shopping portals a commission on purchases made when customers "click through" their web site. These sites return some/most/all of that rebate to you.
Fat Wallet has no referral program, but if you are not a member of eBates, and would like to be, let me know and if you sign up, we both get $5 added to our accounts.