Demoquin said:
enough to have the mafia go "Hey buddy, where is our cut?"
For the Cleric depending on alignment ... i wouldnt even give him gp for his services. He is doing what he is suppose to do. The mage is a diff matter on the other hand
I'd disagree on the cleric not getting money because he is "doing what he's supposed to be doing". NPC clerics charge for healing or resurrections, why couldn't the PC cleric?
Your best bet on limiting is the use of power groups within the city. If the wizard is offering teleports, have him be visited by representatives of the Wayfarer's Guild (from Complete Arcane) unhappy about his unauthorized services. If he doesn't toe the line, he finds himself shadowed daily by a rogue/sorcerer with a wand of Dimensional Anchor. Even if you don't have such groups in your world, there's always that pesky percentile roll. After all, the wizard cannot possibly be "very familiar" with that many destinations, and there's a limit on how many places he could consider "studied carefully". Eventually he's going to be asked to go somewhere he's not familiar with, and the roll will come out badly. I don't think the customer will pay for being teleported somewhere hundreds of miles from where they wanted to go.
As for the cleric, there's got to be other churches in the city, right? They might not appreciate the PC cleric 'freelancing'. Even if it's the cleric's own church in the city, his superiors might not appreciate him bucking authority and performing unauthorized miracles.
Another big factor you can use to limit all the PC's get-rich-quick schemes is simple economics. 95% of the people in any city are going to be commoners and experts whose annual income is measured in the dozens of gold pieces, not the thousands. If Joe Fighter walks into the local gambling hall and plunks down 5000 gp on the craps table, he's probably going to be politely informed that the house can't cover that large of a bet, that the table limit is 5 gp. THe kind of casinos that could handle a 5000 gp bet are probably very exclusive, invitation-only establishments, and the PCs aren't on the list.
As for the 5% of the population that probably could keep up with the PC's financially, it's likely that they've already got arrangements for anything the PC's could provide. "Teleport? No thanks, have a negotiated contract with the Wayfarers. Cure Disease? No thanks, just had one done last week by my good friend Cardinal Fred."
All that being said, don't just forbid your characters from doing some gambling, just make sure they understand that they're not going to win or lose more than a few gold coins, because no one else in the city can afford higher stakes. Don't tell the wizard he can't try to sell a teleport, just make sure he knows beforehand that there are groups in the city that might oppose him. And don't tell the cleric he can't ask for gold for healing other NPC's, just make sure he understands his superiors might take issue with it. Then let them decide if it's worth the risk, and enforce consequences if they do it.
In the end, there's a hundred ways to "beat the house" and make money by exploiting the rules. It comes down to this; do your players want to be adventurers and fight monsters on game night, or be accountants and fight tax collectors?