If you can get OS 50sxh engines for $89, buy all you can and I'll give you $100 each. Last one I bought was $159. I can't get the old 46fxH for $89!
Unless the cylinder or piston is scored or burnt through, all you should need is a new ring. If the eingine has no compression, it's likely the piston has a hole in it. A new piston and ring should be less than $50.
Matt