I have two of those little fellows. And I like them. They were my first motors. 1971 model in really good cosmetic and excellent running shape and 1965 model that I originally bought for a less than $50 for a parts motor. But I ended fixing the parts motor up. (It is running pretty good, but I have to locate a exhaust leak on it. It is a bit of a Frankenstein, because it has lower unit from a 1967 motor and exhaust house from a 1968 motor and couple of minor thing....lol) Sorry back to the point at hand! They are nice runners when service well.
They can be hard to work on due to it compact design. More parts are now not available from the product house. The parts for the carb kit and lower gearcase are about twice as much as others because of there unique design. Parts for the ignition are still standard and no increase in cost. These motor have been known to have exhaust leaks from 3 notable areas and two of the replacement parts are no longer available, but still be gotten from salvage yard and collectors excess collection.
So, unless that motor is in really good running condition and requires no maintenance or repairs then $200 to 250 would be a good price. But if you really want that motor then you would use your judgment....it only $50.00 off.
I would suggest being a little more patient and looking for a 9.9hp Evinrude/Johnson motor 1974 to 1990's. It it is only 0.5hp higher, but the way they were design and regulation of determining horse power change, so they are superior in design, power(much more), and ease of maintenance. Parts are easily available and used good part are easily available. Maintenance is much easier. The cost of a good running motor could be anywhere from $400 to $600 depending on location, market demand in your area and cosmetic and more importantly running condition)
Here is 2 links for a little read on both. You will notice the 9.9 has more reading (Much more popular motor)
Read this first about buying a used outboard motor---> https://www.sschapterpsa.com/ramblings/tips_on_purchasing_OB.htm
https://www.sschapterpsa.com/ramblings/OMC_9.5.htm
https://www.sschapterpsa.com/ramblings/Johnson%209.9_15.htm
(Very good list of reading for couple of different hp of motors ) https://www.sschapterpsa.com/ramblings/OMC/OMC%20info.htm
Good luck.....I hope helped you out and not complicated things for you!!