Starting this thread to help us poor folk. Please add to to make changes if you know better then I. I am a Mage and do not know other classes so levels might be slightly less for meatshields =)
Approximately Level 40 to Level 100 ~ Clear temple - yields 2317 each time.
Level 100 to Level 175 ~ Clear Mines (if you have halls equip) - clearing and collecting the high gold chests yields about 2500 minus the 800 Inn cost each time.
Starting at Level 170 ~ Spider in tomb - yields 3400 until about level 185 then you get an extra 600. As you level up you will be able to kill him more times
before you have to heal at the Inn so you will get extra cash as you level up.
((I will keep editing to correct and add to this as i find them and level up))