There's the banker woman in Drangheim who gives a 20% bonus everytime you deposit and withdraw money. 10 minutes of repeated deposits and withdrawals at the bank will make you 50 Million credits quickly. No more money worries ever. Then fire her and hire a fighter.

If you think that's cheating - use the Master merchant exploit.
This works great with a Lich because at GM learning, he gets many extra skill points to place in the merchant skill. At Master level 25 merchant, the lich buys everything at a deep discount and sells at market value. You can buy everything in the game, enchant it, and sell it back for major bucks. Repeat as often as you like. Once you clear out a store, it will restock as soon as you save and reload the game. So you can make as much money as you have the patience for. Or, sell all your artifacts to the black market ladies in Thjorgard. Then buy them for pennies and resell at retail as often as you like. With 30 or 40 artifacts, the Master merchant lich can make a million gold each time he does it. Occasionally, after moving 300 or more items through his inventory, he refuses to hold anything because of a little bug. Just save and reload the game to reset his inventory counter. For something funny, you can get the lich up to Master level 35 and then the trainers will pay him when he levels up. HaHa - He becomes such a great merchant that they pay him for the honor of training him.

Set a beacon in the dragon cave next to one of the black chests. The dragon won't appear when you beacon in and the chests reset for each trip. Pop in as many times as you want to raid the chests and collect all the game's artifacts. Once you have all of them, your Lich can sell them over and over.