Bought this one for 40€:
https://www.louis.eu/artikel/t-t-tac...umber=10034533
Works great. Connected the red wire for 12v power to the horn (added a fuse box with 10A fuse), black wire to the bolt between the coil terminals for ground, and the green one to the negative terminal of the ignition coil. Adjusted the number of the cylinders so it doesn't double RPM. I only need some kind of a handlebar bracket to make it look a bit better.