Body carts. Have you built one?

I am getting stared on my 71 Duster restore and am looking at body carts. Has any of you built your own? I like this one http://store.uscartool.com/mopar-car-moving-wheel-set.html but cannot justify the $400 when i maybe able to build for less than half. Anyone have any plans/dimensions for building your own?

Thanks a lot.

What would you Justify? Make an offer.

I will not be using these again my project is done. UScartool and fabricated lifting extension that bolts to the front dollies for installing and removing motor/k-frame package.