That thing looks like a steal. The engine sounds like it needs a new OIS (optical ignition system) which runs like 400-500 bucks. I want the arch off of it.
I was thinking about checking it out, but it sounds fishy. The guy claims to have paid $6000 for it in the spring and now hes willing to take $3100. I'm betting he took it to a mechanic and they told him its going to need a rebuild or some big money repair and hes looking to get out of it.
$3100 for a 96 hull and trailer (if in good shape) isn't too bad though. A good used 150 shouldn't be too bad on price if the engine needed to be replaced. Just my $.02.