Hi boyersj,
Jermy4’s comments are right “on the money” 
The link in the tutorial that has much more information about all the variables that can affect durability and the useful life of a mattress relative to each person is post #4 here and the posts it links to.
Post #13 here and the posts it links to has more information about the most important parts of the “value” of any mattress purchase. As you can see I would make sure that you know the specifics (type and quality) of all the materials and components inside the mattress.
It’s certainly appropriate to ask and it should also be on the law tag but the type and quality of the materials would be a more important factor in the quality/durability of the mattress and making meaningful comparisons with other mattresses than the name of the manufacturer.
I would always make comparisons between “mattress only and mattress only” based on the quality and merits of the mattress on a suitable support system in the flat position. Adjustable beds are more of a “commodity purchase” and since they all perform similar functions choosing an adjustable bed is more about “features vs price” comparisons than choosing a mattress which has many more variables involved. There is more about choosing an adjustable bed in post #3 here and the adjustable bed thread that it links to. If you can’t find out the price of each individually then I would look for the same adjustable bed and deduct a reasonably low price for that adjustable bed from the price of the set and use this to make meaningful “value” comparisons with other mattresses.
If both the mattress and the adjustable bed that are sold as part of a “set” turn out to be the best “value” for you on an individual basis then of course it can also make sense to buy them together as a set but I would be cautious about comparing “set” prices to “set” prices because it will make meaningful comparisons for each of them much more difficult.
Phoenix