Overheating

I have a 2001 Toyota Camry, last year started overheating,
so much so heard it boiling after turning off, so I busted the
radiator, got new one put in, coolant and water, well still
overheated, not all of sudden after driving for a bit, pull over
let cool put water in it, found that my fans weren't working
unless I turned on heat or air, And I found that ever since I
had it No Thermostat!!! mechanic said no big deal, didn't
need it????? Well now it's doing it again , We've already
replaced  water pump, needed!! that worked for awhile, still
no thermostat, Now mechanic says 2500 to fix, gaskets, or
replace motor. What's Up??? who's Right???