Crutchfield has higher prices but everything has full factory warranties, service is excellent, and the return policy is the best you'll find. They sometimes have very good prices on closeouts of previous models.
J&R Music (jr.com) and OneCall are both good places to buy from, and J&R carries some factory refurbs (by the factory not the store) with factory warranties. They each might sell some grey market products with house warranties* but most items are "white market."
* I don't know of any specific products, but I've found grey market items at almost every online store except Crutchfield. You can always go to the manufacturer website to check if the J&R/OneCall listing isn't clear.