You can finally get some Sekisui 5760 double sided Thermal Tape at NCIX-
NCIX.com - Buy Sekisui Thermal Tape Sekisui Product Code 5760 25MM (1IN) X 50 Meter Roll - SEKISUI-5760 In Canada.
It's 25 bucks for an absolutely HUGE roll (1" X 50 M) so more than you could use in a lifetime but might be worth it if you were sharing it with some other people or were a pro builder.
If you think that 50M might just be a little overkill, I did find it on EBay for 4USD for four feet of it. Probably someone with a 50 meter roll decided to make a little money
Sekisui 5760 Dbl Sided Thermal Tape; 4ft, 48in X 1in - eBay (item 180301747374 end time Nov-23-08 12:08:04 PST)