Welcome to the Speakerbuilder.net discussion forum. While being polite and respectful is not common on the internet, please try not to flame people who don't deserve it. Otherwise, go nuts.
I have used with great success a foam mattress topper- it seems to have a good density and it's the 1 1/2" size that everyone recommends. Here in T.O. you can get two of these for about 30 bucks - the ones I got were for a queen size mattress. Hope that helps.