Between learning new skills, buying new equipment, restoring HP and MP, keeping buffs running, and especially splurging on food and booze, being an adventurer is an expensive proposition! Fortunately, there are plenty of money-making opportunities available to citizens of the Kingdom of Loathing. The Cobb's Knob Treasury is always full of Meat, and the goblins are notoriously easy to fool. Those with a "meaty thumb" can harvest the orchids, bushes, and trees sometimes found in a Clan Rumpus Room. Of course, if you're not above that sort of thing, you can just beat up monsters and take their Meat.
For more suggestions regarding how to keep your books in the black, check out Basic Farming.