Here's a smaller one I made for a production at a local elementary school. The "roof" is tall to allow the kids to be seen behind the cart.
The ornamental detail (close-up below) on the middle of the wheel is actually functional; it beefs up the wheel so its more stable on the axle & less wobbily. The wheels were from a 2-tiered round table that was scavenged.
Total cost = $25 for the two table legs. Everyhing else was leftovers from previous projects. The cast & crew will paint it at the school.