Re: A Zombiemageddon Campaign Journal - Please read and comment!
I wish the campaign I'd been in was so skillfully done. The DM started us out on an undead-infested world, but stopped after a handful of sessions (and the introduction of an epic wizard as our benefactor).
I took over the campaign, and what I ultimately decided was that the epic wizard (who was from a different setting, as were a few of the PCs) was actually there for the purpose of quarantine only, and wouldn't interfere much in the affairs of the players; mostly she was working with other epic wizards to cut this world off from the rest of the multiverse. She could allow trans-planar trade at exorbitant prices, or allow the party to exit in order to trade, but they would be watched closely and kept separate from others.
Dunno if that'll help you with the loot idea, but there's an option. I wish I could tell you it worked out well, but we disbanded for other reasons after a year of play. I wasn't really that experienced at D&D either so I'm sure I botched some things, but it was a lot of fun for all of us.