That does seem expensive.
There are two Walmart blue pads. One is flat and costs about $6 and the other has an egg-crate pattern and costs $12 or so. The more expensive one is what I have and it works great. The cheaper one seems to have larger bubbles in the structure of the pad so I'm guessing the insulating properties are not as good. The more expensive one is what I think of as a CCF pad.