I'm more on the 'value' side but with a few requirements:
Must be able to support a lot of weight, two people.
King Bed.
Frame better be metal. ( is metal actually more stable?)
The budget is $500 or below.
Mattress: comfortable, budget IDK.
Sofa Bed, big, comfortable.
Regarding the mattress, what is comfortable for you?
A lot of people enjoy soft beds that they can "sink" into… you can probably get one of those for cheap.
I, myself, have had back injuries in the past, and am frequently tight after a whole day of sitting at work, or after doing sport/workouts. Because of this, really firm mattresses are comfy to me. High quality, firm and supportive mattresses do not come cheap, from what I've found.
Firm ones. What is the price range of king size?
For a bed base, you could look at these:
https://yona.com.au/products/cardboard-bed?variant=402973404…
Folds away back into the box, but I'm wondering how to manage the mattress?
2 thicc dudes doing intensive activities..
Noice.