...just a silly question, but if you never used it - how do you know it has 15k on it?
you may want to post some pics...probably would help your cause. "practically brand new" and "15K miles" creates uncertainty among buyers. pics would probably would help you sell your clutch. good luck!
Imho, would be too risky to do all the R&R of a clutch job to put a used unit in. Most likely why you have no interest thus far.