Realhotstuff, in my opinion, is the absolute best site to buy your flash carts from. All my orders have showed up in two days, and they have excellent customer service.
I haven't bought from DealExtreme before, but I really don't feel like waiting two weeks to a month for my order to arrive. And then what happens if my cart arrives faulty, or becomes faulty shorty after I get it. I'll have to send it all the way back to Hong Kong, and have to go through that wait all over again.
DealExtreme has good prices and free shipping, but I would rather pay a few extra dollars for piece of mind through RHS.