One thing I found useful for some needed cash early in my last playthrough, was to sell potions. Namely lvl 1 dex pots. I found the basic ingre for it to be very common throughout the valley. As I didn't need those pots, and just the ingre sold for only 1 gld. I purchased the formula for around 300 IIRC, and made a up a stack of pots that sold for 1300 gld. (26 ea) You can make more gld per ingre if you use lvl 1 formulas than, lets say lvl 2, which uses 2 ingres and sells for 46 gld.
This can be used for some easy cash early in the game or any time prior to the tower.
