If you want infinite amounts of gold (and have patience), try this technique. Buy and equip a Buckler, and head to the Eastings Merchant, who has an incredible array of powerful gear. With the Buckler still equipped, opt to sell it to the merchant. You'll get 7 gold for it, but it'll still be equipped on your character. You can then do this over and over again for infinite gold pieces, but it'll take a while to build a substantial amount up only seven pieces at a time.
Stat Manipulation
When your character levels up, you have to go through a process where depending on their class and level they will get certain statistical bonuses that are randomized. By saving after your character attains enough experience points to level up but before you actually level up the character, you can manipulate your statistical bonuses, resetting the game until you get the statistical bonuses you desire.
For instance, in terms of hit points, which is based on a character's constitution, you can raise your character's hit points by waiting for huge constitution bonuses, resetting your game until that bonus is attained. This is a really useful trick to make hugely powerful parties. It just requires some patience.