My guess if it runs good, and the internal wiring still has it's insulation in place, it should go for $400 - $500 on ebay. I sold an 84 model 25hp on ebay for $650 and the guy paid shipping, (fed ex) to NY, an extra $178!
I crated it real nice and secure for him. He took it directly to his Marine Mechanic and had him go through the usual. He wrote me back and said
that it checked out just fine and thanked me for the bargain.
A 15hp will push a 14' aluminum boat like a mofo. A good friend had one with it and it cruised very nice. Check out ebay, and the prices they are going for. There are bargains to be had if you are patient enough though. Perhaps your friend will sell it to you for a bit less if you take him out. Good luck Chef!