Whatever someone will pay for it, they are pretty rare.
I dont think they are that valuable however, if anyone cares about my opinion. One of those things that not many have, but not many want either. Keeps the price low.
The cart can be had for 80-200. Lowest on ebay around 250 that are stagnant. There is a “kit” minus the roller on ebay that hasnt been touched in weeks for 450$.
Good luck with sale, OP. You might get more hits if you throw a number out there. I feel like the cart is the main draw, separate if you want to move a portion faster.
If no one makes an offer, reach out and I will.