For my D6 Fantasy game I am running, we are using the Funds mechanic.

The idea is even more abstract: Funds represents your ability to purchase things. You roll against the difficulty to acquire something.

Minor treasures, like the coins in the caravan guards' pockets, are ignored.
Major treasures, like the entire contents of the caravan's strongboxes, is listed as a bonus (say +10). These are temporary, use once and lose, bonuses.