Just Butt?

I had surgery in 2006, lost 150 currently at 150 (goal).  I had panni/TT in 2007 due to hernia and skin.  I have been considering getting my butt lifted lately.  Ive seen it done as a belt but not as 2 separate procedures.  Has anyone had just their butt done?  Would there be medical necessity or is it just cosmetic?   And if anyone has had it done what is the approximate cost in US?

I've seen several people on makemeheal.com that have had it done in two stages.  I doubt it would be a medical necessity though.