the cost which people do not consider is ones own time, effort, and struggle which is spent on those dead chewed engines...
I started my experiments from old japanese engines and soon realised that it was useless and waste of time and money and the struglle goes un accounted...
People mostly ask me why new bike engine is so expensive when u can buy a margalla/cultus engine for 1/4th of the price what they do not understand is that car engine has a worth of 0 when it arrived after being chewed abroad already. And the new engine has yet to start its life yet...
these days chinese branded new engines have comparable longer life to japnese counter parts... (not to be confused with chinese copies and replica low quality ones)
so its always a better idea if swapping a new one instead of getting abused in used scrap market..