I made the boxes on mine, 1/4 ply wood and 2x2s, couldn't see pay'n over $100 for someting I could make out of scrap wood. I think they look great too. Anything I can make, I do, and thats a lot...

you can check out my pictures "Explorer 500"

 

I have a metal lathe, so I make a lot of my own bushings, or if something wobbles out-of-round, I weld it up & turn it back true if possible.
Lately, I got an axle, ball, and coupler from NAPA, and built a trailer around it with steel I bought. For not knowing what I was doing I think it turned out OK