Digital Juice Drops
Yep to what Fred says is true, I was going to purchase a design from Aurora Graphics, but found out the shadow was built in and not on a separate layer, (not editable) that nixed the purchase.
However, I love using Digital Juice Drops, every one of their backgrounds is offered in layers, and you can turn each layer off or on, mix layers from other images and best of all, NO End User License Agreement that prohibits the licensee (you) from ever selling their licensed rights. You can find them for sale on ebay all the time.