At this time (late 90s) there were few, if any, specialist robotics suppliers. I had neither Lego Technic nor fischertechnik available, and Mindstorms hadn't been invented. Neither did I have much cash nor all that much time. (Don't let anyone tell you that teaching is an easy, nine-to-five job - it isn't, not if you do it properly.)
I did have a Meccano set (similar to US Erector set), and used that to build my first experimental robot chassis. Meccano parts are mostly steel and the gears were brass. It worked after a fashion, but was very heavy, and quite slow and noisy.
A practical robot was going to have to be scratch-built, as far as possible from scrap or stuff that I had lying around, which is harder than it sounds.
I toyed with several chassis designs, then hit on using the cover from an old 5.25 inch hard drive. It was a high quality product - rigid, easy to mark and drill, not too heavy and a suitable size with convenient fixing points. And free. All I had to do was grind away a couple of small internal fittings.