My daughter is a cheerleader so we buy her Nike Pros (spandex shorts) at Dicks Sporting Goods, Academy Sports, etc. If you want less expensive try the athletic section of Target. Sometimes Dicks has flash sales online and you can get the Nike Pros really cheap. If you want some fun, funky patters, look at "Volleyball Shorts" websites like 'Funkadelic Sports Shorts' or Spotterz. My daughter liked the funky patterns when she was younger, but now likes just Nike Pros.
I just googled Funakadelic and I think they may have went out of business. Same for Spotterz. The younger kids are very particular I think and refer the Nike now. They are no longer considered "bike shorts" but sports shorts or compression shorts since almost all female athletes wear them for various sports, even track now.
Sketchers Go Walks and Mary Jane crocs. A warning though, when the Sketchers got wet, they were not fun to walk in. This year I'm bringing a cheap pair of flip flops for any rai storms we may encounter