I have one of these, they are great. For those taking their form study very seriously, they in particular can help you understand the relationship between form changes you make as they relate to spin, velocity, nose angle, and launch angle; these can be tricky to fully understand. There's a popular youtube channel (Overthrow disc golf) where they use these as part of their very thorough analyses.
That said, you can buy these things: https://shop.techdisc.com
I don't know about competition - I'm an ultimate player who stumbled on the disc golf stuff and then just got really envious.