I agree... they are verrry expensive. Sears probably has a better sale.
Oh, another thing that you could try that is a cheaper option, Lil Me, is to buy this extra padding from Costco. My grandma-2-be has this extra padding on her bed and she says that it's the best thing. I haven't tested out her bed yet, but will soon because I'm looking into one of these for now before I can afford something better. At least, I'm not sleeping on my guy's OLD double-sized FUTON!