The problem the server has is that people are willing to pay over the odds for some items which then causes the price to rise. If a new player see's someone buy a key for 1 million, then the new player also wants to get 1 million for there key which causes tension.
The trouble with setting prices in keys, is that most items are worthless compared to keys. As said before, keys are around 800k, if you look at the list posted by Sweet, hardly any other items are worth anywhere near as much.
lockpick- 450k
The thing about this is that keys and key frags are not valued to us as the price we buy/sell them, when we are buying an item we would rather pay in money over keys, because keys have the second use to open things. We like to have that option of uncrating, and money has only the use of buying things.
This is a very good point and I intend to change the actual use of cash. As of right now, we have a lot of people sitting on their money with nothing to spend it on. That will change; there will be a second hand shop which will offer powerful items (which you would normally not be able to buy), but with an insane price tag.
That sounds like a nice idea, and maybe you can be able to buy an item that adds an open socket to normal items (ex. Socket tool)