I've got two cx2's that are for sale. I have bought and sold on sites before (got a great deal here). My question: What is the best way to insure that you will be paid? With the last deals, we just trusted each other both mailed on the same day and everything worked out fine. I know I can build a positive dealer record on this site but how do you know about the person you're selling to? Any ideas?

I would not be worried if I'm the seller. A seller don't have to ship until payment is verified or received.
There's no way to cheat a seller (especially if the shipment can be tracked).