You could have gone to a sporting goods store and purchased an inflatable camping mattress and saved 90%. From a cost vs comfort and durability, you should get any pocketed coil mattress brand that feels good and buy the lowest cost in the construction you like. Beautyrest is the original maker using this construction, but Sealy has just started using it after knocking it for decades. S&F is a Sealy property and they also offer, at higher prices, similar constructions.

If you don’t need a foundation, the absolute best pocketed coil mattress is not available in stores. You have to go to the website of Charles P. Rogers beds who have been making this construction since the nineteenth century and sell factory direct.

I have used a Tempur-Pedic pillow for more than ten years and it has not deteriorated even slightly, but I agree with you as to the initial feeling on their mattress. Memory foam padding in innerspring mattresses can be the ideal combination because the visco-elastic foam’s softness does the trick. You are coasting for a disappointment with your two-side adjustable plastic bubble. If you can return it for credit and get a proper mattress, you may someday appreciate my advice.
Marshall.