It's probably just me, but I think if the 6-8 people mentioned trade big amounts of coins, then the coins will get spread to the other players, and the economy will flow. It is unavoidable that the $$ rich will have the advantage (FYI, I'm a pure free credits player, so I suffer as well), but once they use their coins to trade for the items they want, then the coins will spread to the others. Now without a price limit, they would pay higher for the items they really want, because they will value their silvers less-simply because they have so many of them. But if there's a price limit, then those with a lot of silver can just offer the items at the limit price and buy (then hoard) more items due to the lower price.
@storm: I believe that people would want mroe than 3 of the role related items, especially as their role grows. It is probably one of the reasons for Kragel and my role, to create custom items for people who want to compliment their role more and more. And for those custom-made items, I believe it's ok if they don't want to trade it out, even when they have more than 3.