Unlimited money
This trick requires a summoner with the skill of alchemy to transform items. As this can be exploited at the beginning you can get rich early on in the game (if you are VERY patient). To do this you must transmute a orkish brandy (costs 25 gold) into either a small healing/stamina potion (both sell for 33 gold). The gain isn't much (about 8 more gold) but it's still a gain. This trick can be repeated as many times as wanted.