In need of opinions and inputs?

About a month ago in school, my friend dropped her things off her desk onto the floor, I tried to help her but I was sitting in my desk and it tipped over onto her stuff, but not her. Turns out, her phone was inside of her folder and one of the corners of my desk landed on it and dented it. It was completely an accident and note that I had no clue her phone was inside her folder. Later that day, she texted me after her parents decided to ask if I would help them pay for a new or another phone, since her phone was not fixable. My parents agreed to helping them out, and for the past few weeks my parents and her parents have been on the look for used phones. The other day, her parents decided on if I could just help pay towards a phone. I was not personally aware that they wanted to upgrade to one of the iPhone 6 's, her broken phone is an iPhone 5s. My parents talked to her's today and found that out. They are asking for $150. We had originally agreed to paying half the cost, but they didn't make it clear to me at least, that an upgrade is only around $200, luckily my dad knew that… The bad part of this all, honestly, is that the girl and I are pretty close, but our parents have never met or anything. At this point, my parents aren't too happy about this but we're willing to be decent people and help them out, but I will also take responsibility because I was in the situation. What is your opinion on this situation?

An accident is just that you don't need to up grade you need to get her back to where she was only. I watch Judge Judy and Peoples Court. You are not responsible to do more than make her whole again. Do not over pay. I think it was her fault altogether. She dropped the phone.

I think its completely not your fault. After all, you ARE clueless that her phone was in her folder. Plus, she shouldn't have put it in there, a pocket would be nice. And I think her parents are asking for too much. It was just a dent, right? Do they really NEED to upgrade it to iPhone 6? I want to write a whole paragraph, but this is fine too.
This is my opinion.

I don't think you should have to fix it, youre not the one that broke it