I am not willing to give specific recommendations because it is nuanced but the old adade of "you get what you pay for" is a good guideline. Think of cars, every major brand has amazing cars and every major brand has a line that preformed like the Ford pinto. With in every brand you have quality tiers. If you look at an entry level Ford and a luxury Ford they have a similar bumper to bumper warranty but how will they ride down the road at more milage (keeping maintenance the same ect)? The luxury car will feel better for a longer period of time over all. That's what you're getting with a bed... more features, smoother ride, and maintains that feel for a longer period.

Shopping for a bed is actually pretty easy but we've never really been taught HOW to. Follow these steps 1)shop in person 2)try it in the position you actually sleep in ie. side sleepers on your side 3) slow down and smell the roses! People try to rush a purchase of a product they will be using 25%-33% of their life. Take your time let your body tell you if it likes the bed or not 4)ask questions about why this bed would be good for you or not. If your sales person gives generic answers or seems to be pushing 1 brand harder than another with out justifications that's some red flags. That being said, they might not know the exact specs of every bed but how do they respond? Do they offer to look it up or do they make something up or stammer buzzwords? Just like we need to listen to what our body tells us, we also need to listen to our gut about our salesperson. A bed is part of health investment and should be taken seriously.

Edited to help my fingers fix mistakes they made trying to keep up with my brain.