I'm thinking of buying a bed... Do you know the brand BestSleep?

‌Right now, I'm just sleeping on a heated mat on the floor...
My back hasn't been great lately... so I'm thinking of buying a bed...
I used a bed in the past, but since I bought a cheap, unbranded mattress online... I feel like my back was completely ruined back then..ㅠ
Anyway, even if it's not high-end, the brand I can afford to go all out on within my budget is BestSleep..
Roughly in the 400,000 to 800,000 KRW range.
But it seems like this is only the price for the mattress... Even looking at their Naver Store, strangely, there is no price information for frames.
They only seem to sell mattresses.... Do people only use mattress pads these days?
In my opinion, the frame should take up a significant portion of the bed budget...
Anyway, this brand seems to be used by athletes and supplied to hotels...
I'm planning to visit an experience center tomorrow... Is this a good brand??