Lipo is a procedure. How much of it is required varies from person to person. So there is no 'one fee' for liposuction. In our clinic I assess all patients and then determine the cost based on how many areas are being treated, how much is being taken out.... all this really represents how much time the procedure will take. A shorter procedure is cheaper, a longer procedure is more expensive.
The other factor is the complexity of the procedure. Some are simple liposuctions, others may require finesse which means going slowly and carefully, again adding to the overall time of the procedure.