not sure on the typical used price (you may want to also look into the cost of a refurb, another good alternative) but i still think a 1" is going to be too big for your setup even if you swap rear disc brakes on. think about the size of the stock brakes on an s2k or dc5 and compare them to the size of your's. if they aren't close, then its the wrong mc. don't just think about rotor size, i'm talking about caliper piston size.

Just trying to point you in the right direction

-Luke