Right now, we can store 1 billion in gold on a vendor, but we can only store 125 million in a bank vault, and we have to remove every item other than gold in order to do so, because our bank vaults will only hold checks, and won't allow us to store our gold like we do on vendors. The really, really rich may have several billion gold on their vendors, but they can't buy a castle in-game because it would cost a billion gold, and there is no way to get that gold off their vendors and into a backpack to trade for the house deed. The Devs should just make a system so that we can store large amounts of gold in our bank accounts like we can on a vendor, and use that gold to buy a castle, large house or other major purchase. Placing a check on a banker NPC could make it add that amount to our bank account, just like the gold on vendors works. Then house purchases could work like when we tell the vendor how much to withdraw. Just state the price and it will be removed from the buyer's bank account and put in the seller's when they trade houses.
In real dollars, 10 years ago, a castle was worth maybe $1,000 or 10 to 15 million gold, when gold was worth about $75 per million. Now, a castle is worth maybe $1,000 or 1 to 1.5 billion gold, when gold is worth about 75 cents per million. Not much has changed in terms of real money. But UO's inflation has increased as much in 10 years as real-world inflation has in 70 years. It's about like paying $12.50 for a movie ticket last month to see Avatar, when tickets were 10 cents in 1939 when Gone With the Wind was the big hit. My granddad paid $3 per month house rent in 1939, it's $650 today for the same house. A 10 pound bag of flour was 5 cents. Now, it's $2.99 for 5 pounds. But he only earned $5.50 per week working for the county; now, they pay $480 per week for the same manual labor job. In real terms, things haven't changed much. The overall standard of living for the same worker today is about the same as it was back then.
UO is dealing with the same inflationary spiral that the real-world money supply is dealing with, except that it's happening a lot faster than in the real world. We earn a lot more now than we did 10 years ago, but nearly everything we buy in the game has likewise become more expensive, except the items that have been subject to governmental (or game system) controls. Economically, it's a stalemate. If inflation keeps going for another 10 years at the current rate, gold may be worth a penny a million, but that castle will be worth 100 billion gold or $1,000 in real world money.
The historical solution to any fiat currency has been that an country's money supply eventually collapses, becomes worthless, and is replaced with a new currency that is backed with something of tangible value, like gold or silver, which has a limited supply and can't be counterfeited easily. UO may eventually have to replace gold with something else, once inflation has made million-gold checks so worthless that people want to barter items or deal in real-world cash rather than use them as a medium of exchange, which has already happened in the case of really uber items and large houses.