[mistercrash]

I like the fact that they sell 2.5 mm. I bought a lot of CF from Full Force RC and I love their stuff but they have 1.5 mm, 2 mm and then jump to 3 mm. I bought from Penguin RC when I needed 2.5 mm.
As for their prices, Hobby City is the most expensive of the three mentioned in this post, but only by 1 or 2 pennies per square inch.
To make shock towers, Penguin RC sells 4 mm thick CF.