WalMart has the Spa Sensations 1.5″ Memory Foam Mattress-Topper for a low $61.95 (reg. $68.84).

A mattress-topper that provides remarkable support. This unique Theratouch high-density memory foam immediately responds to your body shape and weight. When reclined upon, it will gently mold itself to the curves of your body, and simulate a flotation effect. All-natural hypo-allergenic Jacquard cover included.