Yeah KX parts are expensive.
But look on Ebay, you can probably find a good used set of cases, cylinder I would just have re-plated, by like US Chrome my dad has some done there, I think its about $200 and it will be like new.
And you can get aftermarket brgs, gaskets, etc. to put it back together to save some money.
I can get a good deal on aftermarket parts if you need anything let me know.
good Luck!