She called about the logistics of trying to get refunds for some of the stuff, and gave me a brief apology about about the canceling. I said something like, "Frankly, it wasn't a huge surprise. You do this often." and brought up the ski-trip incident. Her reply was that she didn't remember that - no apology. And then she became very short with me on the phone. Since then I've only had brief emails about refunding aspects of the trip. Oh well - at this point I don't think we have much to say to each other. I suppose I'll just leave things where they lie and write off the friendship for my sanity.
(re: bolded) She is lying.
She might not be lying. It didn't inconvenience her, so why should she remember it?
It's like a relative of mine. She had a row with her SO, who told her that she sometimes said really horrible things. She complained to me and said she doesn't. I backed her SO up and told her some of the things she'd said to me. She didn't remember them. Why should she? They didn't cause her pain. I, on the other hand, do remember them. I'm sure her ex-SO remembers the things she said to him too.
As for Flaky Friend, she wasn't inconvenienced at all. At the time, she blew it off as nothing important, so why should she remember something of such little significance? The fact that it is significant to other people either hasn't occurred to her or just doesn't matter.
Good for you, OP, for calling her on it. If she has any respect at all for your time and money (and your friends' time and money), she'll stop this. But I suspect she doesn't and won't.