AIBU about my friend not asking me about the price of a shared gift?

[Museumland]

Me and two other friends decided to club together for a fourth friend's 40 birthday. We agreed to take her to an outdoor show picked by the Birthday girl. There were various ticket prices and she emailed asking if we would spend £70, £80 or £90. I emailed back and said £70 would be fine. An hour later she emailed to say she had booked the upper price tickets plus a picnic table (with no food, literally a table) for £50 And programmes and with booking fees to be split between us... the gift isn't for a best friend but a close one.
AIBU...to be annoyed. It's done so I can't say anything more and she earns less than me although is very casual about money..

Id email her to say that you thought you’d agreed to the £70 ticket. You could say that’s what you budgeted for and see what her response is. When I do a group present I ask how much do you want to contribute then buy based on that.

Is this £90 each or altogether? Plus another £50 and then split three ways would be just under £140 each. Thats outrageous!! ( or maybe i am misunderstanding you)

Yes I would be miffed if we agreed a budget and she didn't stick to it. You could say you're only prepared to contribute your share of the lower prices ticket but i suppose it wont make for a fun trip. Probably best to tell her you were disappointed she did that and leave it at that. Don't pay it if it leaves you in a spot financially.

You're right it's £140...part of that is the cost of my own ticket of course but I am rather miffed she bought the tickets without waiting for a response to her question..