Is it way below the flood plain or anything like that? Building a massive pad isn't cheap. That's the first thing that comes to mind.
Also, why would he ask you to go 1/2 if that's all there is to it? Just a question to ask yourself. I wouldn't give up a potential $40k just because we're buds. But maybe that just me.
Very sell-able and desirable area.
How long has it currently been on the market, or is it?
I'm just trying to help you find any negatives. Good luck