I sold a fife (sort of like a recorder, but played like a flute) on ebay for £20, when I had only paid £10 for it a few years earlier, so I bought some more, and carried on selling them for quite a while. I actually sold one for £46 and a second chance for £35. I actually felt really bad about that, but they seemed happy enough! Unfortunatley eventually soem ppl cottoned on and I got undercut by the music retailers, but I had made £200 profit in total.