I am in the process of building one now....trying to build it cheap but functional. I got a hub from a go-cart for the hinge and put in on a piece of all thread. It looks like the all thread in not going to be strong enough to hold the weight, but I am trying to re-enforce it.
Long story made short---get the good parts in the first place. I have put alot of hours into what I'm doing and I'm still not sure its going to work but I'm already so far in I can't give up.