some manufactures offer a "pre run" new engine....Ed is one i know of...so it would be a JS I think Nova does as well........but usually only in the .21 size i dont think it is offered in a .18
a Piston/sleve is ony 28$ us......it may be worth fixing....you need to have it looked at before you spend anything on it though like mentioned above.....
http://www.amainhobbies.com/product_...n-Cylinder-Set
the crank is 19$ us
http://www.amainhobbies.com/product_...ankshaft-GXR18
also these parts would require to break-in the engine like it was new.....the new engine is 145$ us
and it still might not be worth it if the bearings are shot as well.........then i would look at something like this LRP 115$ us new......if you plan on fixing it you need to have it looked at before you spend anything like jaz said.......
http://www.amainhobbies.com/product_...e-w-Pull-Start
I usually use a rock or screwdriver to stop my flywheel...