The same price gouging is going on with the LCP...people think it's a "hard to get" gun, so they pay too much for it. I have a feeling that's why these XDms cost more. Only because people are willing to pay it right now while it's a new gun. I bet nobody will charge more than $550 a year from now..
That being said, I picked up the XDm and it really feels great. I had two XDs and sold them, but regret it. They are fine guns, and I hope to add another one to my collection of handguns, which currently consists of a Glock 19, USPc40, Colt Commander, and Kimber Ultra Carry II. I really want an XDm40 in OD/black for a nice woods gun, but might go with a 9mm instead due to the anticipation of a Glock 20SF 10mm being released at the upcoming SHOT show. I'd much rather carry a 10mm into the woods over anything else.