cost of rebuilding a KA, possibly for boost

[darknightMR2]

well fellas, i cant find a good motor than anyone wants to sell, or at least one that they want to get rid of for cheap. anyways, i have a KA24de that has a knock, well i was wondering:
what pistons should i go w/, or what do you guys recommend(possibly boosting in the future)
should i need to replace the rods(im boosting low 7-9psi)
what cost should i be looking for this to run

i know these are pretty vague questions, but i need to get an idea of cost, and where i should source these parts from. i don't know if it would be more cost effective to rebuild what i have, or source a drop in motor. most ive seen have 100k + and they want more than 500 bucks. i don't see paying that, if it cost less to rebuild, but i know that pistons alone could cost more than a motor. any help would be appreciated. thanks!