Normally if players want to make money off some piece of loot they found adventuring they've got pretty much one choice: Sell it. To a shop, private individual, institution, doesn't really matter. Find a buyer, negotiate a price, and sell it.
My players weren't satisfied with that (and also didn't have the time to find a buyer or reliable fence), so I made some rules for auctioning off items to let them sell their objets d' art (of questionable provenance) quickly and for a higher profit than a direct sale would net them. Here's how it works:
1) Players set:- A starting bid. (A bid of 2x market price or more for an item will decrease the amount of bids they get later by 5 because fewer people are interested at that price.)
- A reserve price. (Optional. If the bidding doesn't meet or exceed the reserve, the item won't be sold.)
2) The Auction House sets:- The percentage of the proceeds they will take from the final selling price as payment. (I set mine at 15%.)
- The number of days needed to publicize the auction. The standard time is 3 days, but the players can request more days to bring in more people or fewer to sell the item and get their money faster. (No more than 7 days or the public's enthusiasm will wane.) The number of days publicized is added to the roll that determines if a bidding war can start or not.
3) Bidding:- Roll 1d8+2 to determine how many bids there will be. Once you reach the number of bids rolled, the auction ends and the item is sold. (If the players' starting bid is 2x the market price or more for the item, give this roll a -5.)
- Increasing the bid: For each bid roll 1d10. Each 1 is worth 5% of the current bid price. A bid can't increase an item's price more than 50% unless a bidding war starts.
Ex: For an item at 100 GP: A roll of 1 is 100 GP + 5% = 105 GP for the new bid. A roll of 8 is 100 GP + 40% = 140 GP for the new bid.
- Bidding wars: These can start if there are more people in the audience. Roll 1d12 + (number of days the auction was publicized), on a 12 or more a bidding war is possible. One will start if the current bid reaches 2x the starting bid.
In a bidding war roll 1d10 as usual, but each 1 = 10% instead of 5%; and roll 1d6 and multiply the d10 by it.
Ex: 1d10 = 5, 1d6 = 4. 50% x 4 = 200% bid increase.
So to make this happen:
- Players set the starting bid (and reserve)
- DM and players agree on the number of days publicized and the Auction House's cut
- Roll to see if a bidding war might start
- Roll to see how many bids there will be
- Roll the bids! (If you hit the 2x starting bid threshold and get a bidding war, switch to the higher increase rate and rake in the gold.)
- Bidding ends when you reach the number of bids rolled at the start. Take out the Auction House's cut and give the party their money.
This obviously involves more effort and math than a direct sale to an NPC, but it's worth it. Auctions are much more engaging than just getting [X] GP from a shopkeeper. If the rapid-fire math aspect concerns you, use a calculator. I definitely did to keep things moving quickly:
[Current Bid] * 1.[% from the d10] = [New Bid]
And this is important: Let your players roll everything. You don't touch any dice. Have them take turns rolling the bids while you tally up the current price. Watching the DM roll and do math isn't fun, rolling to see how much money you make is.
If you want a ballpark idea of how much an auction might net for your players, here are examples from my game: My players had two hyper realistic (read: medusa'd) sculptures up for bid, one deer and one squirrel. The deer had a starting bid of 260 GP and after 10 bids got 2397 GP. The squirrel started at 80 GP and after 4 lucky bid rolls got them 317 GP. After the auction house's 15% cut they walked away with 2307 GP and change. And that was without any bidding wars erupting.
If you want to keep the party poor, auctions probably aren't for you. Otherwise, give it a shot!