Re: What is a fair price to pay for this motor?
You need to find out if it's a '76 or later, or earlier. If earlier, then it has a mild steel drive shaft and is likely pitted and won't hold a seal. If a '76 or later, it has a stainless drive shaft which is much better but just as likely as any motor to get a groove in the seal area over time. It's easy to tell, though. Just run it in a barrel for a few minutes and remove the lower oil drain screw to see if there's coffee/milk, or water. If so, it's not worth diddly to me. IF the lower unit doesn't leak water in, and it idles good with good compression, then I'd go with the $500 already mentioned as a fair price range. Those lower units were very tough, and the powerheads were great on speed and power. Other than electrical parts and carbs. that liked to be spotlesslessy clean in order to crank easy when cold, they were super good until the seals on the lower unit started leaking water in. It takes a real sure-'nuff merc mechanic to get one of those merc 200's back in good shape.
Just something to think about and my opinions only,
JBJ