This is a very broad question, because the reasons for revision are many. Time can allow the breasts to change, so sometimes a lift is needed as well. Sometimes the pocket enlarges and the implants are displaced to the side or downward. This requires particular correction of the pocket which can be time consuming. There is the problem of hardening or capsular contracture. When the capsules are removed and new implants are placed, this is also time consuming and adds the cost of new implants. Probably the least expensive revision is simply a change from saline to gel, or a change of size. In this case there my be no need to do anything with the pocket or capsule, just open the previous incision, remove the implants and place new ones. This is the quickest kind of revision surgery. However, some women also want considerably larger implants than they started with, e.g, 250 to 425. In this case, the pocket needs enlargement and this can take time. Generally I would release the capsule and use sizers to make sure there is no restriction to the new pocket when the larger implants are placed. All of these variables mean a revision can be a brief straightforward implant exchange, or a complicated many hour procedure to repair an enlarged pocket, remove capsules and change implants from above to below the muscle or vice versa, use acellular dermal matrix (800/sheet) to reconstruct the pocket and prevent recurrent capsular contracture, and possibly a mastopexy or lift as well. Costs could vary between 4,000 to 10,000 or more. The answer to this question entirely depends on the clinical details, so an in-person consultation with a board-certified plastric surgeon is essential.