haven't seen any staintune stuff for sale 2nd hand - just got a new termi kit for my MTS for £565 incl airbox lid, filter, ECU. have you checked
www.multistrada.net for similar sales? am looking for header - have been quoted around £250 +vat for new(staintune), there was a DP header on e-bay recently - not sure how much it went for, it was upto £170 when i looked.