This is easily obtained with a friend or co-op partner at the very first Tomb which is called Timekeeper. Simply have you or your partner collect all the gems and kill all of the enemies you need 75000 for Gold.
Shoot all the Vases and collect the gems from them also drop bombs on the destructible parts of the ground and light all the lamps. Kill all of the enemies and you should have 75000 way before the end.
Its virtually impossible to do this solo as there isn't enough gems to collect, I tried and finished with just over 50000 getting all but 1 Vase.