HI Melinda,
Congratulation on planning your first trip to Walt Disney World. Your 4 year old Princess will have the time of her life running around the parks. While Walt Disney World always gives its Guests a first class experience in every aspect of your trip, they do offer great options for those of us on a budget.
I would say your first stop on the Walt Disney World resort website should be
Disney's Value Resort Hotels. This is one of the best ways to save money while visiting, and still feel like you are part of the pixie dust. Our family's favorite Value Resorts are Disney's Pop Century and Disney's Art of Animation. We love Pop Century because the rooms are fun, and they are big enough for our family of 4 to sleep, relax and take quick mid-day naps during our stay.
Art of Animation is an all around beautiful Resort, with room themes from The Little Mermaid, The Lion King, Cars and Finding Nemo. I think your little girl would really love to stay there for her birthday. A stay in the Little Mermaid room is something that she'll remember for years to come. The best part is that they rooms are affordable. Lodging while traveling can easily take you over your budget, but Walt Disney World makes sure that is not an issue by offering stays at Value Resorts.
There are tons of other tips and tricks I can share with you, so please feel free to ask me any more questions about your upcoming vacation. I'm excited to help you and I hope to hear from you soon, Melinda.
Have a fantastical Disney day!