One way you could completely get rid of gold sellers and keep prices resonable would be to put some sort of cap on the prices of items being sold. Now for most MMO's this suggestion wouldn't work as items in most MMO's don't really have a listed market price. But for this game it would be very easy to implement. Just set cap of 2x the actual market price of the item. Gold would no longer need to be bought from gold sellers as prices would finally be reasonable and you would no longer see insane high prices on weapons that are effectively +3 or higher. There's really no reason anyone should have to pay 100k on a freaking +1 Holy Keen Adamantine weapon when it's market value is only around 9k.
The only people who would really complain about such a bold move would be the Gold Seller's as no one would need them anymore. Give gold back it's value and stop the recession.