Well, that's good. Buying a car in a rush is a pain, so I'm glad you managed to buy yourselves some time.
Bummer that your sister can't go. I like the idea of getting her something special. Maybe you could get her a little special treat, like Mickey-shaped pasta, or one of those snack mixes with crackers shaped like Mickey heads or whatever? I tend to think of those as "a little piece of Disney magic". If she's a pin collector, there are a couple of pins connected to New Fantasyland out, and a lot of cool stuff in the store in Belle's village -- a light-up cup and things.
OTOH, since she can't go, maybe you'd want something not so park-specific; there's a cart in downtown Disney that has some nice stencil art if your sister likes cats, and a lot of beautiful pieces in Mexico, China and Japan, both cats and dragons and (in Mexico) just about any other animal you might mention. My girls and I had fun perusing the big store in Japan; my sister had just gotten back from Japan when we all got together at Christmas, and we found a lot of the kind of things she gave for Christmas presents there!