The cost of one CREDD is set by the player. The easier it gets to obtain money, the more people want to buy CREDD, the higher the cost will rise.
No, that isn't the case. All MMOs have a exponential curve of gold being worth less and less, to a point where gold is nearly worthless (take WoW as an example). That means that prices are literally unstable 24/7, one morning it's high, the next it's low. MMO's arent real world economies, you are talking about a population of players taht ranges from 14-20 years old for like 80% of the population. 99% of the time the AH is just a undercut fest without taking minimum regards to inflation or other shit, so no Mr. economists, this is MMO world not Wall Street