My father owns a mattress company, and I feel like this is a continual thing.
Tempurpedic is not proprietary, we make the exact same thing as Tempur, we get it from the same supplier, it is absolutely identical. However, we sell at 1/4 of the price. They have to pay for the advertising somehow...
Memory foam comes in a variety of densities, we make custom firmnesses by using different density combinations, and even his/her side mattresses out of memory foam. Id recommend a non-tempur brand, just ask for the desnity specs and make sure you're getting the same thing.
Latex is worth looking into as well, I've slept on a huge range of latex and/or memory foam beds over the years. My favorite is one of our combo latex/memory foam beds, the best of both worlds.