The XT ones differ from the regular Deore in that the housing is cast AL on the XT and just stamped steel on the Deore (or something like that, I'm working from memory). I don't know about the DX version, as I've never seen a DX thumbshifter. From what I've seen, the XT version usually bring about $70 on ebay, much, much less for the regular (steel) Deore. I have no idea why these ones are going so high, perhaps because they are NOS.