I use a lot of tufnol strip as insulators and brush ring gear on electric motors.
The link Jason gave is the company I use and I have found them to be the most cost effective company and believe me when you are paying the bills you do look 
I keep every thickness in stock up to 12mm but unfortunately I only order in 600mm or 1M lengths max as i never have to do long peices and it's easier to store in 1M lengths than 2M