So, what you're saying is because her grades are bad she has to be locked away and have no freedom at all in an unscientific unproven way of 'helping' her?
A few people say TBS helped them when the vast majority says they were abused, neglected, and not helped at all, so it's worth a shot for you - but she has no say in the matter?
Because you have gaps in parenting you think a fly-by-night institution with no medical diagnosis, diagnostics, or proof of efficacy is the best way to fix her because why?
Bad grades and disagreeing with you is called being a teenager. You say you had the possibility of going to a program, yet you turned out fine without. Why is she different?
If you're convinced she will be a 'loser' on account of disagreeing with her parents or having mediocre grades, and the only way to fix that is alternative medicine, you've been sold a good line from an edcon. There is no problem except the crisis of conscience. Bad high school grades really don't mean a damn thing. I personally dropped out on account of high school being worthless and that I found out that it was; when I went to college as a mature adult I got a 3.75 GPA and I'm now a paid undergrad teaching assistant and paid tutor, with everything covered by grants. The point of this being that if someone convinced you high school is some kind of do-or-die-moment, or that 18 is, that's false. There is absolutely no emergency and certainly nothing worth locking someone up over.
Nevertheless, programs don't fix anything and have never ever been able to prove they have. Ever. They play off of general, nebulous fears and then claim to fix general, nebulous things - and if the kid doesn't act perfect, they generally go very far out of their way to say the kid should be completely cut off from the parent until the kid turns around. Read up on exit plans sometime. Certainly not anything worth $5K a month and a daughter being held incommunicado indefinitely until eighteen, now is it?
However, the real question is how much is it worth to ameliorate your well intended but misdirected sense of worry. If she's not committing crimes, and she just doesn't care about what you care about, is that worth losing 60,000 dollars and your relationship with your daughter? Is it worth what you'd be doing to her, when nobody seems to know what is wrong or what will happen? Sending someone to get reprogrammed because you think she's 'going to be a loser' is going beyond the pail to address your own worries about her not being perfect. She's a different individual from you and eventually you'll have to come to grips with that, be it now, at 18, or whenever else.
This is a decision you will regret almost immediately, and when she's had to deal with months of abuse, bullshit and powerlessness, the only fault for her not having a thing to do with you would rest on your own shoulders. $5K/mo can do a lot, but it's your job to figure out what to do - not to let some people selling empty promises to allay fearful parents take it, and your child, and not even give her the right to speak to you or a lawyer without them cutting her off if she says what they don't want.
You wouldn't give her a pill if there was no proof it worked, so why would you lock her up for years?