Hamels is a free agent after his year and is easily affordable by the Yankees, even with luxury tax implications in mind.
He might cost one good prospect and maybe an ancillary minor leaguer or two who have potential but eventually never see an MLB game played before September 1.
If the Yankees can get him for Cody Carroll and Mike Ford, think is that too much?
I could see them parting with, say Domingo German as well. (But not with the other mentioned names. Instead of.)
Bottom line - getting Hamels won't hurt the Yankees in any way. Cashman isn't trading his blue chips for a rental, and no other team can match his return...