Perhaps a market could be created for users to sell, (at a fraction of the cost). This would be for items currently available at the mall/furniture store. And resale could be restricted.
In addition, older users can sell items that are no longer available to newer users. Such as older holiday/event collections, and free gifts. This would be for items no longer available at the mall/furniture store.
Also, clubs could have resale fundraisers, competitions, contest, and exclusive invite only glam sales. The game could charge an entry fee, a set-up fee, a list fee, and or a percentage of the total. This would be a win/win for but the users and game admins. Some resales could also be hosted via game administrators to users whom have spent real money; and or for a small real money entry fee, like .50 - .99 cents.
For items purchased with emeralds and diamonds you could use the current exchange rate less 40% as the resale value.
Thank you in advance for your time consideration.