There's different types of TT too. I think you've got a regular one where they cut a section out and sew the top to the bottom. Then there's a fluer de lis (sp?) where they cut along the bottom and also up the middle, like an upside down capital T.
The first one can cost as little as $1500 if medically necessary (going by what my friend told me, who had just that done). The other can be $4000+ (that also could be if medically necessary, as my friends was).
Don't take this for gospel though! Just trying to remember the info my friend shares with me