I started tray heating with an aqarium heater, and moved onto a water bed mat type heater placed on top of some silvered bubble wrap insulation. My stainless steel food srevice type tray goes over that when I need a heated tray option.
Control started with a SCR based light dimmer, and has moved on to a PID controller salvaged from a commecial refrigerator control circuit.
When powering USE a GFI/RCD with all of these options.
A former independent commercial distributor, Treck Hall, has been gobbled up in the last 5 years by Unisource.
If you set up an account with them (basically give them your credit card #). Two days later they have you set up in their system. Then they will quote on your order. You accept their quote, and they ship to their nearest commercial warehouse, which is likley close to most larger Canadian cities. You give then a few days to ship to there, and can pick up at their warehouse with no courier fees or hazmat shipping hassles. They do have delivery options, which can dramatically push up the cost of a small order.
The trick is to know what Kodak cat# you want, that they cross ref to their intermal stock #. I looked up the Kodak cat# on the b&h site the last time I ordered from Unisource.