You can buy the heads on ebay, like I said, I've bought at least half a dozen dental heads and other tubes from ebay sellers and nobody has ever asked for any sort of certification. As far as anyone is concerned, I'm buying parts, not complete machines, and they're for collecting, not operating. Same with film cassettes and film. Not sure what you mean about having to dispose of lead, the film just comes in cardboard boxes with a light-proof plastic envelope inside. To develop it you need ordinary photographic film developer and fixer, I bought that from a photographic supply place called Adorama. You can get developing trays but they were a bit too small so I got a couple of plastic storage bins at Target that I use as developing trays. For the safelight I used a small red LED bulb in one of those socket adapters that plugs into the wall. I never worried about precise developer mixture and temperature, I just watch under the safelight while agitating the tray. It takes about 10 minutes to set up the darkroom, a minute or two to develop each film, then hang them up on clips to dry for a half hour or so before handling.
Are the rules different in Canada than in the US? I was offered an xray machine some years ago from a vet clinic in Canada but I didn't want to try hauling it back across the border. You might check ebay for items already in Canada, film for example, I bought a lot of it as expired stock which was cheap. I bet if you ask around at hospitals and vet clinics you can find some expired film, speaking from experience it works just fine, even expired years ago. I use my own film when using the big machine at my friend's business and I'm still using the film I bought back when I started doing this stuff.