I know my answer is no fun, but this sounds like an excellent opportunity to teach her some of life's lessons/money matters...
When my daughter wanted a second doll, we gave her the opportunity to save her allowance ($2 per week), birthday money, and extra "bonus" money from being mom's helper over the course of the year. Yes, she was not thrilled with the fact we wouldn't buy her another doll, but the lesson was important. At age 7, she saved up almost $75, and when it was time to get the doll, we covered the rest. She had worked hard all year, and she did learn the value of $100. It became a good tool throughout the year that taught her the value of a dollar. "Yes, I know you want that (whatever), but did you know it costs 1/3 of an American Girl Doll? Think about which one you would have, then make your decision."
The good news is that she has an entire year to save up! Lots of time to help out, save some money (while still being able to spend a little throughout the year). It will make her doll an even more special purchase!