I think you should buy the slightly thicker 1.5mm foam - the 1mm is very floppy but 1.5 mm is stiff enough to use in modest amounts with no additional support. BTW, big bonus is that you can solder onto it very easily with ordinary multicore solder as used for electronics.
Power supply looks like good value. I have two home-brew ones in the lab, Each has 3 channels with voltage and current control up to 60V and 15A perchannel. The driver unit is a 2kW server PSU. The parts were all cheap enough. I'll find some links. And a picture.