They do look good - and simple - and cheap!Bowie, if you’re getting a welder just get some 20-25mm SHS lengths and dolly wheels and make your own. Measure them up for length and width so the tyres sit nicely in the rectangular frame but allow the tyre to sit high enough off the ground to not catch or drag. I used the dolly wheels that have a threaded centre stem and put nylon nuts on top. I’ll see if I can find some pics.
I’ve also built a series of stands over the years to support and move cars around.
They look fairly high, are they like that to work under them, and do you just jack up one wheel at a time, or front and rear both wheels?
To just move a car around, it would be easy to make a lower set of course, it's a good idea all round.