The chest you spoke of isn't much, but if you take it every time you pass it can add up.

Same with the trolls in the Gol'Galath path. The first troll has a key to the room north of him that contains like 800 copper. Everytime you pass. He is two rounder once you get past level 20 or so.

The gem in campfire south of wood-elf city. Worth a pretty penny or a barter and is light. Grab it every time you pass by.

Gems in Svirfnebli city gem garden. Not worth much, but good for getting a quick bite to eat in an emergency.

TIP: Always try to barter to save your coin, but try not to barter super expensive stuff for crap. If you don't know the value of the item you can: use lore, use identify, use Alduk (Inn of the Eternal Star), or you can take it to a shopkeeper that would buy it if they had money and type "valute (item)." He/she should tell you how much it is worth if they had the money.

Level 1-10 Kill goblins in the Silverwood. Take all the peridots and give them to the guy that gives you money for them.

Level 11-20 Kill goblins in their hidden fortress. Slow leveling, but the coin adds up and you can practice your skills.

Level 20-30 Clear the ruined keep. Every guard has decent money. The bugbear when you can take him does too. The sergeant's chest has money as well. Be careful as this is typically a high traffic area for a number of reasons.

Level 30-40 Frost giants

Level 40-51 DRAGONS EVERYWHERE!?!?!

These will net you plenty of money to buy the few preps you probably know and buy equipment fromt he bazaar/various city shops that you might like. Beyond that you will have to learn the more advanced techniques in game or from your friendly neighborhood cheat ring.