I posted thoughts about these earlier this month and in the end ordered a Raskelf. I have just used it for the first time this weekend and was pleased with the difference it made to the bed.
I ordered the 2" and was glad I did as I feel the 1" might not have been thick enough, but I have to say that the beds in our caravan are VERY hard. The Raskelf rolled up neatly and went under the bed quite easily. I would be interested in trying a cheaper one as a comparison but you have to make a decision in the end and generally you get what you pay for. Hope this helps!