You have some time before your trip, and it's never too early to start teaching her some good habits in spending money anyway. I started with my girls as soon as they got the concept of money, probably around 5 years old,
When we took our first trip to
Disneyland 2 years ago, I gave each girl a small notebook (it had princesses on it of course) and then carried those in their fanny pack. Whenever they saw something they wanted, I had them write it down in their notebook....item, price, and store where we saw it. If they later saw it at another store we made an additional entry so we weren't running all over the last day.
Then on the night before our last day we went over all the pages they'd written on and started eliminating items....these were over their budget, these we could get similiar at home or online. The most important one I had them concentrate on then was how long it's life would be. We'd already worked on this a lot at home with everyday things, so they understood this concept a bit. For example....buying the pretty pink purse full of candy was only ok...the candy wouldn't last more than a couple days (even if they could resist it would be hard and stale in weeks/months). The purse however they could use over and over....so I asked them if they thought the price was worth it for just the purse. Nope, so we eliminated that one. Then it was the toys....well, yes, those last a long time, but you have other toys for playing make believe and these aren't exact duplicates but they would replace what you already have, so that might be a bit of a waste of money. But if it was something very different from everything you have already, then the question becomes will you still want to play with it next month? Tshirts are always a good thing because we usually buy them a size larger so they'll last for 2 years, this year a little large, next year just right. And just go on and on like this until you have the items left to get.....and at this point if their budget doesn't quite reach I'll help out so long as they've made wise choices.
This doesn't always work perfectly, we've bought a lot of junk over the years, but that's a whole other lesson in itself. While I don't nag them about it, when we get home and a month later that cheap toy I tried to talk them out of breaks or is just sitting in the toy box, I remember that to use the next time we're debating a purchase to remind them that a prior decision wasn't as well thought out as we'd hoped, or that it seemed like a good idea at the time but then turned out to be not everything we'd hoped (either because of quality or because they didn't use it as much as they thought they would). I think it's probably just as important for them to be allowed to make those choices that we know will likely backfire....because they need to know it firsthand. I just choose to make sure those lessons are hard but not catastrophic or a ridiculous waste of money.
The notebook approach also teaches the VERY important lesson of not going for instant gratification every time. There are so many things that they could want over the course of a week or two at WDW....if they were to spend it all in the first couple of days, then what happens when they find the one thing they really want, but are out of money because they bought a bunch of cheap junk. This is very hard for one of my daughters whose favorite line is "it's just a dollar". She never has as much as her sister to be able to get the nicer/expensive things because she has squandered her money one dollar at a time.
The other big advantage of the notebook.....it's often that as we go through the list to eliminate things, they either can't really remember what that item they wrote down was, or can't remember why they really wanted it. It helps with those heat of the moment "I gotta have it" feelings, that later would turn to regret because it was just not truly something they wanted.
As for adding to her cash....I'd hold off. Know in your mind that you're willing to supplement her purchases if she needs it, but telling her that ahead of time may backfire if you're concerned about her frittering it away. By going through something like I described above, you can then decide to reward her thoughtful choices when she has whittled the list down to two items and can't afford both but is having a tough time choosing. "Honey, I see you've made some wise choices here and I know the final choice is very hard, so how about if I help you out and you can get both items." The look on their face is worth every penny! And....that way if I don't like either of their choices, I'm not contributing to their folly.
Good luck! It's never too early to learn these lessson. I have a 30something year old sister that I wish I could teach in this way. Maybe she'd not be struggling to make the rent every month!
)
We actually did really well in the spending department this trip. We told them to take their time each day and look around and then later on they could decide what they wanted the most. My oldest DS did great with this until he received a dream lanyard that came with 2 pins and then he got hooked on pin buying. Then towards the end of our trip, he discovered that the Shop in Japan sold Pokemon and he was upset he could not buy very much. So now our next trip all his money, or at least the majority of it, will be spent in Japan!!
