I want to stop inflation in a virtual economy

So I want to make a minecraft server with a TRUE economy. That means that there's no store, rather their is an auction house. The problem is, that if I let everyone start out with, say, $50000, there will be more and more money going into the economy, making it worth less and less. Is there any way to stop this?

Have a system that compares the total amount of people that have ever joined the server with the prices of the products. As more people join, prices gradually increase creating fair sale prices. The problem is how much should the prices increase per additional player. For that I would come up with a formula and apply a general flat increase by a certain percent to all products. Just as an example, you could have it so prices rise x1.03 (0.3%) each time a new player joins.

Update: haha just re-read auction part. Yeah, its difficult because you as the "Government" have no control over prices. I would overhaul the system. Make the starting amount 10,000, and if you can, set "Quotas" that will help to regulate the prices. Other than that, I can't offer any advice based on my knowledge.

As more and more people join give them less and less? Lol

Don't let it. You're the boss.