The cheap kits can be ok. I have 4 of them and they are all just fine if you don't need the best and fastest. They do need to be checked over for casting issues around the ports. Decking the cylinder, intake manifold matching, a better wrist pin and some spacers on either side plus a NGK plug they are just fine for most uses.
I don't want to go much faster than 30 mph and if I can climb the hills were I live, good enough for me.