remounting the motherboard is the best option make sure nothing is shorting out on the board ,and everything is reconnected, that leaves the psu to be the mostly likely bad part . if a new psu doesn't solve the issue than its the gpu .
Getting parts on a limited budget : Buy parts from places that offer 30 day returns send back if you don't need it ,watch for restocking fees.This takes extra time to troubleshoot and fix but if you only have $200 to fix it ,It's a great option.
Btw if you touch the metal of the case with bare skin(wrist,arm) do you feel any kind of shock?