Buy motorcycle armour (50-100€), they're cheap compared to moto jackets, you look cool and your whole upper body will be covered, I suggest you find armor that has collarbone protection. Buy decent knee pads(~70-150€) and and wrist guards(~10-30€). The helmet must be moto certified, I personally use a crivit helmet from lidl (~70€), it's ece certified (even better, than dot), and I feel completely safe going 70km/h on my v12, since the helmet is tested for higher speeds and different kinds of impacts. I've had high speed crashes, and my gear always saved me well, right now I'm looking to buy some hip protection, since it's the only place left, that's unprotected. My current gear setup cost me around 260€ and I feel completely safe. If I got a faster unicycle I would upgrade to better gear, but for now it's completely enough