If you're looking to save up cash, the volcano is a good place for it. The Hot Dogs and Magma Men both drop Rain Staves on a frequent basis, which not only kill most volcano enemies in one hit, they sell for 2000 gold apiece. I made a cool 26,000 out of the deal.
You can also come back to the volcano after clearing it to reach a previously inaccessible area and get a bag of gold and a Confuse Charm (forgot to get screenshots, sorry).
