You can also check birthdayexpress.com
I think they have Peter Pan birthday supplies (just not the Disney Peter Pan). In January, my daughter wanted a Peter Pan b-day party, but we settled on a Tinkerbell party - I found Tinkerbell party supplies at birthdayexpress.com.
She wore her Tinkerbell costume, my son wore his Peter Pan costume, DH wore a Captain Hook costume, and I wore . . . well . . . a Wendy costume!

Everyone invited was encouraged to come as a Fairy, a Lost Boy, a Darling child, or an Indian.
The kids made pirate hats, & we had a treasure hunt (led by Captain Hook) at the end. I found a lot of good party favors at Oriental Trading Company - fairy bears, pirate eye patchs, treasure chests, jewel rings, etc.
I put both Peter Pan toys & Tinkerbell toys on the food table & made a Pirate Ship out of a watermelon. My menu included - -Peter Pan peanut butter sandwiches, Fairy Bread, Smee's Cheese, Jolly Roger Fruit, Croc Chips, Captain Hook Planks (carrot & celery sticks), Pixie Garden Flowers, the Darlings' Petit Fours, Tinkerbell Cake, & Mermaid Lagoon Punch. At each table place setting, I had a small little cup of Pixie Dust (yellow cake glitter) for the kids to sprinkle on their food.
Edited to Add - We used a Tinkerbell pinata, but you could also use a Crocodile pinata. I thought about it, but for my daughter's 4th b-day, we did a Disney Princess Party & used a Dragon Pinata (for the "Slay the Dragon" game). And, for my son's 3rd b-day party (a "Finding Nemo") party, we used a shark pinata. So we wanted something different.