I'm keen on the genuine Prusa i3 MK3 kit, but it's a hundred dollars higher than your top end budget reference. It's worth every penny, though, as the support forums that cover the Prusa line of printers are top-notch. The kit is quite easy to assemble and the instruction included are probably the most comprehensive instructions on the market. Each step of the instructions also has a corresponding video for even more clarity. I helped the local library makerspace assemble a MK2, which is slightly more challenging to assemble. The printer is sitting idle due to recent regulations, but it ran wonderfully in a public exposure environment, with nearly zero problems. One thing that was learned was to not print on PEI is the same location every time. That's an easy fix.

For the student to develop design skills, consider Tinkercad as a starting point. In short order, he and you may discover that there are some things not easily accomplished in Tinkercad at which point it's time to consider big-boy programs like Fusion 360 (free for hobbyists), OpenSCAD (text based modeling program, good for logical, programmer-type thinkers), OnShape and many others. Developing flexibility in various program use means not getting mired in one program forever and keeping your tool kit filled with many choices.

All of the above is opinion, of course.