where can i buy a jazz dance costume like these?

HI!
Jazz is a great form of dance that I love to watch and perform! Unfortunately, I can not see your example but here are a few places that sell a variety of costumes. You may be able to find one that you like from these:

Algyperforms carries hundreds of costumes for all types of dancers. They have over 8 pages of Jazz uniforms and also a section just for competitions! See if they have the one you want!

TripleThreatDanceWear is one I love for their unique designs. Just look at the Queen Elizabeth costume they carry! They also design and dress people from So You Think You Can Dance! (Love that show!). They’d love to provide the unique dance wear and accessories that you need!

To save money for adults and children, go to DanceDeJaVu. They have the Jazz, Lyrical, Ballet and other costumes you may need for all dance styles in hard to find or discontinued styles. They are also very reasonably priced! I hope this helps and if you have additional shopping needs don't hesitate to ask! Thanks!