Birthday at a trampoline park: is it normal for us to pay as guests?!

So my 9 year old daughter was supposed to go to this indoor jungle gym and trampoline park for a school friend's 9th birthday. It's SUPER expensive so I've never taken my daughter.

She got an invite from a school friend. The invite didn't say anything about there being a fee. I assumed that like most parties, it would be a given that the host pays for everything. If there was going to be a fee, I would have expected it on the card or said when we RSVP'd.

Well we get there, and find out that we have a $75 fee to pay to enter. I said I didn't realize we had to pay $75? I'm a single mom and don't have that kind of money to just throw around. The mom explained that this is the cost of the party divided by the number of people coming (so the space rental). This is the mom, NOT THE PARK, explaining this. The park had nothing to do with this interaction.

I told her that I can't afford the money to pay and she said that's a shame because now my cost is going to have to be split between the remaining people and two people already cancelled for the same reason. I was very embarrassed and said I misunderstood and thought that because she invited us here, this was on her dime. The mom said why would you think you could come here for free? I said we've been to (and hosted) parties and never had to pay as guests. She said "Well this party cost almost $900 so I don't know what you were expecting."

I told her that regrettably I can't afford $75 without notice. I felt awful for my daughter but we had to leave. I gave the mom the card but decided based on the exchange to keep the gift so I could return it. It's not a decision I'm proud of but honestly if my child isn't going to a party, we don't buy a gift and I spent $25 on this gift because it was the cheapest thing on the list.

She's since sent me several nasty texts and I blocked her. I told my daughter that she can play with this girl at school but unfortunately we will not have her at our house. It's not like they saw each other outside of school often but still.

I would have felt icky paying for it but if I had time to scrimp and save I would have.

I just want to know if this is the norm now? Like am I going to have to keep $100 handy at all times for parties? Was I wrong?