Best Performance Upgrades for Little Money - Here's My Vote

I wonder if this might be due to the cheap prices though?
if I can build an engine for 500 dollars I might try it myself, but if it will cost 2500 I might have a professional do it
so the cheap entry cost of a chebby attracts a lot of back yard mechanics, while the higher initial cost of a mopar get more professionals wrenching on them?
The shop that has four race cares and a bundle of doe orders there engines and spend 20 grand on one, send it back for diagnose and buy a new one, each year they get new engines SBC..