Best parental response in the given situation... "TOO BAD! SOOO SAD!"
My sis has Gucci taste, yet has no job and expects single mommy to pay for everything... She has had a serious reality check for her senior year in high school.
If you are paying for it, it should be by your rules with some compromise to accommodate her wants. Otherwise, she should pony up the dough and since she isn't likely to do that... YOU get to go to Moab!
Problem solved!
That's my non-parental inexperienced opinion.