I was maybe thinking, a lot of RPG games nowadays give the players to be able to make money with virtually no limit. I was wondering if this is a good idea, to allow characters to flood that economy freely, and buy great gear from vendors for almost nothing(Which the best gear will never be available from Vendors, but still). A system i was thinking, was a total world proc, that keeps track of every cent in the world Economy. Vendors prices will change depending on the amount of money in the world at the time.

For example, say a world has a 100 Million gold in it's economy, And a vendor is selling a very rare item for 0.05% of the total worlds gold. At the current moment, this magic item sells for 50,000 gold. But if some guy farms for gold for a LONG time, and accumulates another 20 Million gold. Once the gold is in the system, the price rises. The same magic item now costs 60,000g.

A system like this seems like a very modern and realistic scenarios. The only problem is that the gold in the system keeps going up, and never deflates, and for players who don't get anymore gold, no matter how the system is, can't buy the items they need. To balance this out, maybe regular intervals that draw money from the economy and delete it is a good idea, however i would do so like this. When a servers economy is more than say 1 billion gold, the clock begins to tick, and every so often, a small % of gold is deleted from the economy. Gradually deflating the prices, if the total gold in the economy falls below 1 billion however, the ticks stop, halting the decrease until the economy is above 1 billion again.

I'm not exactly asking for help, I was just wondering what your opinions on world economies were like.
instead of a world economy; you could have individual economic variables(shops) each being a subsection of a main economy for example the different Z levels on the map.

Now Items are sold on specific parts of the map(zlevels) and according to some world variable? summer winter or whatever; people tend to buy from different places. Then each economy must battle against each other for the most income; the interface border could act as a sort of advertisement for the shops that invest in that area... and on and on...

We can all read an Economics book about the ins and outs of economy and base this around that. However, who wants to step into a reality based game? why not trash the idea of economy as a whole and invent a new idea? Something players can appreciate. It is a game after all.

This is definitely a economic NO NO. You're halting the growth of your economy and I am 100% sure that players will be VERY angry about losing money all the time, not to mention how unfair the system is.
Perhaps if you made a set limit to how much gold is in the world. Say 1 hundred million gold, then an economy system could work, And in reality it would regulate itself. For instance,

There is 1 hundred million gold available. That gold is disbursed between 5 major banks which lend out money to people who decide to start a business. Then those people have to buy supplies and make a work force that they pay creating more jobs but also creating supply and demand. This does 2 things essentially. Spreads the money out equally and makes the money rotate because in order for people to do there jobs they have to either pay someone else for the materials or they need to make them there selves. In which case you have a constant flow of money that is limited so that it doesn't become crazy inflation. Shops will set prices accordingly because they not only need to make a profit but they also will have to keep up with other stores prices. This could be done with a mixture of NPCs and player run shops or all through NPCs or all through players. And it would be an interesting little experiment to see how people would handle there money when there was only so much to go around. The only issue I can see here is money hungry people who would gain a lot of money but not deposit it back into circulation. In which case you could always "tax" the rich or businesses and create some sort of trickle down system to help keep the flow.
What i recommend is try more of something like a stock system as well. so have your shopkeepers have there sellable items... When a player buys the item its brought.. the shopkeeper slowly rejuvenates his stock to a certain limit. when a player sells to a npc it sits there.

Then also have buyable items and non buyables then have unique items only gained from quests/bosses. this way the rarer items lets say Bronze, copper is npc. and moonrock armour is a boss drop.. that way the economy will level itself out and sort itself out. and allow players to inflate/deflate as they see fit. then if you don't like how something is going you can introduce static npcs that will always sell an item without ever selling out for a static price forcing an item down or stay at same price.

I reckon this way it all levels out, but this should be accompanied by some form of crafting system to allow players to also make it.. so not only will you have the finished form for buy/sell but also the raw materials.

It all depends on the game i guess. but thats my 2cents and its pretty standard mmorpg wide
In response to Moussiffer
I have been considering a project with exactly this type of economy. I haven't really come up with a premise for a game though, other than how I would want the economy to work.

Do you know of any games that work this way?
I suggest making the economy a bit more realistic - by using a set amount of gold in the world.

All gold-making actions would draw from this gold fund, and if gold were left around long enough without being picked up, it wouldn't just disappear. It'd go back to the server's gold stockpile.

Also, splitting currency up tends to make the player value a certain type of currency more. Say, you have gold, silver, and copper. Ten silvers are worth a gold, and ten coppers are worth a silver.

By basing your economy around a system such as that, players could be persuaded into smaller-scale, easier gold-farming techniques that seem to produce more than they do.
In response to Rapmaster
I did something like this, a personal economy, player has gold var and a goldALL var every gold piece picked up is added to both although you dont spend the goldALL var it just creates your prices on higher level items, which made ppl pissed that player1 item costs more then player2 item. and ppl complained that if someone spent along time playing the game and getting gold he was almost penalized for playing in that the items cost more to him...

but this eliminates things like players that no longer play for months at a time effecting world economy. or someone who just sits around and makes gold just so no one can afford the high tier items and now he can pk everyone...
In response to Asielen
I can't think of any games that use a system like this. Something similar to this might be the Fable series, but it isn't the same...

It seems like a great idea though if done correctly. If you do make a system such as this I would love to see the finished product. =]
In response to AmandaDD
wouldnt that just encourage people to make alts purely for the purpose of buying out items at cheaper prices..

cause i know i would
In response to Midgetbuster
then so be it for the alts shouldnt be allowed to trade items between each other thus rendering the purchase(s) useless. Also it becomes easier for newer players to start out and the older more common players become more cautious and appreciate their purchases... win/win n'est-ce pas?