I (35F) can't keep up with the constant demands from my teenager (16F)

Yes, I know kids are expensive, responding as such isn't helpful.My teenager (16F) is a good kid. She maintains pretty good grades across the board, even in her AP classes. But I cannot financially keep up with her constant demands. First there is this trip for band in May. We find out the day before the first $50 deposit is due in Sept (which we paid). We told her we really wanted her to have this opportunity to go on this big trip, but she needed to maintain her good grades and do all the fundraisers. Next deposit date came around right before Christmas and she scraped together about $75, we had to pay the other $200. Final deposit of $275 is due Friday, she has raised, in all the opportunities, a whopping $12.70 toward this trip. If we could get what we paid back, we'd try, but we can't anyway, and are planning (with a sweet $100 from my mom) to just finish paying it ourselves anyway.But then on Saturday she needed jeans (fine) and my husband took her to Target where she suddenly also needed a $30 bra and a swimsuit (for her trip). Now today it's "pep gets to go to state on Wednesday. Band teacher says I need cash too." So that's out of the blue (to US, not her). And now this afternoon it's saying she needs brand new glasses (like $200). Which, of course, was also not mentioned before she convinced dad to spend a bunch of money on Saturday. Did I mention we also pay for her iPhone 7?We have 2 other kids. We're not rolling in the dough here, and she has no concept or appreciation at all for the hundreds of dollars she needs on stuff like every month, above and beyond her normal expenses of daily life.I'm feeling so overwhelmed and frustrated with her constant entitlement. Mom and dad are not made of money.I don't know if we should take the iPhone and get her a "dumb" phone while we're trying to catch up paying all these other expenses or what.She gets her snark on that we "don't bother giving allowance", but a) iPhone, b) unlimited cell service, c) bus pass for free reign of travel (with permission of course, she isn't feral); in addition to all the other "little" kind of stuff like lattes and things like that we get her.I don't know what to do or if anyone has any advice. Maybe I'm just hoping someone can tell me how to handle a green eyed monster when they live with you and are your responsibility. via /r/Parenting http://ift.tt/2FaHd1s