So, for me, I crossed my game with a game I used to play called Gemstone. I allow my players to purchase items, but can enhance their stats by combining items together making them 1D stronger. But I also tax them for it with payment. The stronger they get, I make their opponents stronger as time goes on. I'll announce at the beginning of the dungeon that all npcs are 1D or 2D and so on to make it challenging.

I also give bosses a fear factor which reduces all players by 1D when in combat. It makes things interesting watching them work together.

I give out gold based on enthusiasm and role play. They must agree to either share the profits or be greedy. With the ability to add dice to their armor or weapon, sometimes they get greedy and have to ask for help if they are running away from a mob because they went their own way.