I only tested Heaven's Gift up to level 3, where it started giving normal sized potions.
Try buying the 8 or 10 charms you can afford first, and see if you still have a problem before spending too much time trying to get gold with Heaven's Gift. Check out the topic
differences between classes for details on secondary stat calculation, to decide which charms would have the most benefit.
The imp chieftains can drop gold charms, as can the imp riders (less often) IIRC. I entered the wastelands with 29 stacks of 50k gold and 6 gold charms, and by the end I had found or bought an additional 60 gold charms (I think around 8 or 10 were dropped).