Heya Perth... rule of thumb is if you use the same surgeon who put it in it will be done for near bulk billed. Going to another surgeon will see you paying full price. However having said that if you were getting the sleeve done by the same doctor who is doing your sleeve he may do it at a reduced cost.
My advice would be to choose a reputable doctor with a good and safe track record and one you can trust rather than looking for a bargain basement knife man.
If you can, I would return to my band doc for removal and sleeve unless there is very good reason not too.