<human>: Can you give me the gist of the text in a nutshell?

Edit: Okay, I guess I'll wait and see if she brings it up again and see if its sold out. If my back is completely against the wall and those two situations occur, then I'll come clean. Thanks!

I know this probably isn't the exact purpose of this sub, but I figure this is a mix of communication/white lie that I need some serious advice for.

Big win: About 2-3 weeks ago thanks to a hot tip from me mum I buy tickets for my girlfriend and I to see her favorite play, MacBeth, performed in a one man show on Broadway.

Problem: Last night while on the phone the girlfriend brings up the play and even says the name of the guy who is doing it! She says that it'll probably be exorbitant and she won't want to pay for it if it is.

There's an obvious problem here, how do I avoid buying the tickets without acting like a dick about it? 

I can try to stall her if she asks about it but considering it's her favorite play she may not drop the issue until I give a good enough excuse. But if the show gets sold out, there's an easy win.

If I just outright tell her it'll be too expensive right now and she checks the prices, she might get upset or worst case scenario, just buy the damn things herself!

Side note: I planned on trolling her the night of the play by saying we'd have to go to the city for her present. I've been doing game development lately and made a doodle jump clone using stuff from our relationship. Plan to act like that was the 'big reveal' of the night and when she's fully grumping about the crappy present walking her over to the play. Too far?
<bot>: Bought girlfriend tickets to favorite play, she discovered the play and may badger me about buying tickets. Must avoid blowing surprise. Lives under a bridge and wondering if I shouldn't make her pay my toll?