Where to Buy Sheets of Foam Rubber in Vancouver or Victoria?

[Canadian]

When I move my tank in a week or so I want to replace the existing material I have between the tank and stand with a material similar to a yoga or pilates mat. Are there any places that sell something like this in either white or black in Vancouver or Victoria?

Because my tank is small I can probably get away with just buying a yoga mat and cutting it down to size (which was what I originally planned). However every yoga mat I see is some pastel shade of teal, pink, lavender, etc. and I need white or black. Plus I'd rather not have to pay $40 for an overpriced Lululemon yoga mat.