$1500 is fair but not a steal. They are sought after, but its not like they bring big bucks. I have one with a dual carb 750 swap, and it would probably sell for around $2500 tops around here. Quite a few of them are waterlogged. Parts are very hard to get..i looked for a gas tank for a year before finally giving up and repairing mine. I looked for a reverse cable for even longer. They are like a big bathtub in the water...and out of the water that bathtub loves to catch water which then goes halfway up your motor before draining out anywhere.
So you have to tarp it every time..or ideally store it indoors.
Did I mention parts are hard to get?
I am sort of biased right now because I have done way more wrenching on mine than I ever expected. The motor that was in it was an SBT, and the rod let loose within an hour of me finally getting it running right. I sold off all the stock 650 stuff and the upgraded manifold with 44sbn...and dropped in a 750 from a donor sitdown. The stock jetmate ebox and stator are like gold.
