Here are a few to get you started! Feel free to post more in the comments - there are also a bunch of ideas floating around in the brainstorm channel on the discord server.

• blood price: certain actions damage you
• you're a debt collector and have to chase down people who owe you money
• simple arcade "pay to continue"
• deal with the devil - gain [thing] for [unreasonably steep price]
• you're working as a mercenary to pay off something