Pictures?
Although the GA market is depressed now, $15K for a low time later model 150 is a bit lower that what I've seen them sell for...usually a clean 150 with good times on it "usually" starts at $18K and up, depending on nice shiny paint, clean interior and good avionics.
Why a dead cyl after only 516 since major? May indicate a poor "shadetree" overhaul.
If paint and interior are shot, you have to factor that in eventually....