I bought a 600EX-RT and ST-E3-RT through PMI digital and it was a fantastic transaction. Shipped (Free) the same day and I had it the third day. Their prices were all well below the Canon MAP pricing before the new rules of enforcement. Now they list at MAP because they are an authorized dealer for Canon. I have no interest in the group buy but, I think you would be hard pressed to find better prices than what they offer if you just took the time to contact them.