How about a greedy challenge? You can't sell anything until it reaches its maximum possible price. So: no selling fish until you reach level 10 fishing (and choose the profession there that gives you the extra fishing price); although actually you can't sell regular fish at all; they need to be smoked fish. And, of course, you need the artisan profession before you can sell artisan goods. I guess fish that will sell for less than 75 gold (before smoking) can be turned into sushi and sold. Only one piece of each crop may be sold un-pickeld/kegged/dried; the rest must be processed. And so on. You'll get lots of money... eventually. The beginning will be a slog, though. For extra difficulty, do this on 25% profits. Oh, and you can only sell the fishing tackle that you find, not the tackle you make. Oh, and let's put a limit on buying things. You can never spend more than 10% of your total gold in hand (measured at the beginning of that day).
