check compresion, check for spark, check the lower unit for metal in the gear lube. Stay away from motors that have been used in salt water if you can help it. Loop charged motors are prefered(stay away from older John Rudes). Be carefull of the weight(some Yamaha 2 stroke engines are heavier than you think). Stick with a carb motor, you don't need the complexity of efi or dfi. Run away from anything that has Ficht written on it. Be carefull of "rebuilt" engines, theres no telling whats been done. Check Craigs list around areas with large lakes, between last years drought, and this years high gas prices, you may be able to find a deal on a whole boat, pull the motor, than sell or trade teh boat off.
Its a salt water motor, but look for something like this
http://www.charlestonfishing.com/for...il.asp?id=5321