I have an older mattress but no money to buy a new one just yet. I am desperate for a good nights sleep. Has anyone ever tried the memory foam mattress toppers and what did you think? Also I see they run in price anywhere from $30 - $200. Are the cheap ones any good? What thicknesses have you tried and found to be helpful? Cheapest ones seem to be about 1-1 1/2" thick. If I buy the more expensive one I might as well put that money toward a new mattress. So give me all your experiences good or bad so I don't have to learn from my own!