Just a thought - why don't you offer to buy your drummer's mic? If he has the headset mic, he might want the cash more than the spare mic, and you get a mic you know you like for less. Possible win-win.
I did offer to buy it from him, but he's kind of an equipment junkie and didn't want to sell it. He's a really nice guy and never seems to mind loaning stuff out to people if they need it, but he never sells anything. You know the type.