EA would probably be better off as the broker in the deal:
Player A has 30 million gold and wants to sell it for 1 month's game time.
Player B needs 30 million gold and is willing to pay $15 real money for it.
At this point, both players hit a button which takes them to a secure page on EA's UO website, and for a fee of $1.99 real-life money, an automatic system will broker the deal. The players have to work it out between themselves as to who pays the fees; the options would be something like "buyer pays, seller pays, both parties split the fee".
The same system could broker cross-shard trades, too. Player A lives on Napa and wants to buy an item bless deed from Player B who lives on Pacific, for 100 million gold. They go to the secure webpage and EA brokers the deal for $1.99. When both players have hit the "accept" button, one receives the item, the other receives the gold, and EA puts a charge on one or both of their credit cards for its broker fee.
It works as both a way to improve gameplay and a profit center which doesn't create inflation problems.
The way that the vendors work is that the charge is 1 UO gold per 500 value per UO day, 24 gold per 1,000 in value per real-world day. It used to be charged every UO day, but that caused vendors to poof before the owners could put gold on them, so it was changed to once per real-world day. The amount charged is still 24 gold per 1,000, though.
My most expensive vendors cost something in the range of 300k per day, each, plus Luna rental fees of 1 million per week. That's maybe 3 million per week total. If my items didn't sell fast, the vendors would poof. The only way you can have 50 to 100 million in goods on a vendor, while paying both the vendor and rental fees, is if you're selling at least 10 to 20 million per week.
There are several ways to get rid of some of the excess gold in the game. But being able to sell artifacts to vendors would just make the problem worse. Now, buying artifacts, item bless deeds, and a lot of other rare items from exotic items vendors wouldn't be a bad idea. I do like the idea of cutting down the amount of gold that all of the ML monsters give. Any creature that dies within 8 seconds and gives nearly 3k in gold, plus about 20 relic-fragment quality items per hour (Miasma and Swoop), is just ridiculous if you don't want an inflationary death spiral. Making the item drops a lot fewer wouldn't be bad either. There is no need for a level 6 treasure chest or dark father to have dozens of pieces of pure crap in it; you shouldn't have to pick through 10,000 pieces of junk to find that one piece with an imbue value of 350 or more. If its imbue value is 110, it should never spawn at all on anything tougher than an ogre.
A really good spring cleaning effort, followed by an event in which the desperate refugees from Magincia are selling their "family heirlooms", ie a new group of artifacts that are really cool looking and useful but not really overpowered, for massive amounts of gold, then a patch which cuts all of the loot to the following rates:
The lowest-level, 1st tier monsters like ogres and trolls drop less than 50 gold and have a 1 in 20 chance of dropping an item with an imbue value of 150 or less
2nd tier monsters like liches, trogs, etc. drop no more than 100 gold and have a 1 in 20 chance of dropping an item with an imbue value of 125 to 200
3rd tiers like Lich Lords, Ogre Lords, Greater Dragons drop no more than 250 gold and have a 1 in 20 chance of dropping an item with an imbue value of 200-300
4th tiers like Miasma, Swoop, Lurg, Ancient Wyrms, etc. drop no more than 350 gold and have a 1 in 20 chance of dropping an item with an imbue value of 300-400
A few high-level 4th tiers like Rend would drop no more than 450 gold and have a 1 in 20 chance of dropping an item with an imbue value of 350-450
5th tiers like the Dark Father drop up to 500 gold and 1 to 3 items with an imbue value of 400-500 or an artifact. All of the top 10 damagers would get a chance at the item.
Before AOS, you could pretty much depend on low-level creatures never having anything good, and high-level ones never dropping anything truly bad. You didn't get inundated with massive piles of garbage. Now, people often just leave relic fragment worthy items on miasmas because they can't bring themselves to wade through the thousands of pieces of junk to get that one good item.
AOS should have been named the Age of Massive Amounts of Worthless Junk. Sloppy programming that merged too much of the monster loot tables and too much reliance on the great god Random Number Generator brought UO to the point it's at now. A little work to make each monster type's loot table unique again, a reduction in the great ML gold farms, a good spring cleaning and a new gold sink could just make UO's economy viable again.