How about making your own? You have seen ours and know what direction you want to go in. So bend some tube and get to welding? Completely honest here. My buddy that’s big into fabing stuff is really wanting to “copy” the goblin. Not exact, but the concept with a different drivetrain. The blueprint is “easy”, just need to adapt it to what you want.
Take an extended learning course at the local community college and you’ll have access to all the cool tools. That’s what my buddy does (Did before beer flu). He has access to benders, cnc plasma, welders, on and on.
and a good notcher is a must if you are splicing tubing.