From someone who's "been there done that" twice Starting with a $20 investment isn't so bad. If the motor proves solid, get a gear change kit from tytrials in the UK for under $150 or find a machinest who likes Coors light, fenders from dcplastics, some paint and decals and have fun.
When I got my 1st TY175 I also wondered what the deal was with the splined piece on the frame. I never found out what it was for , I worried that I had bought a pieced together frankenbike.
My problem locally is to find enough interest in a twinshock class to even have 2-3 riders.