The top of that unit is made of 100% latex and should last the life of the bed with no problem. Hard to say what a reasonable price is, I sell that unit for $ 4,962 with the box spring and that includes delivery anywhere in the continental United States. What are their prices? <just curious?>

You can save a little money and get the All Cotton with the 4" Latex topper which is virtually the same bed less the underneath bottom pad, and that would come out to $ 3,426 (my prices, delivery included). I doubt you would be able to tell the difference other than the lower overall height.