The mattress I got from Amazon was the Queen 10 inch Signature Design by Ashley (I’m on mobile so hopefully the link doesn’t mess up):
https://www.amazon.com/dp/B07B9KDM5R?ref=ppx_pop_mob_ap_share
I bought the queen for $255 back in November but it looks like it’s out of stock in the full and the queen 10 in. is currently sold by different sellers at a higher price. So I suppose you could get the 8 inch one? The nice thing about this mattress is that you can pay for it in monthly installments too. It’s definitely a bit firmer than I expected based on the reviews I read—probably like a medium firmness. I definitely recommend it though!
I got this guy. It’s been 1.5 years and it’s still pretty firm.
Signature Design by Ashley - 10 Inch Chime Express Memory Foam Mattress - Bed in a Box - Queen - White https://www.amazon.com/dp/B07B9KDM5R/ref=cm_sw_r_cp_api_i_zPWmFb990H926
I have a lot of back problems and loved this one by Ashley furniture. Way cheaper than a lot of other box mattresses Signature Design by Ashley Chime 10" Firm Memory Foam Mattress, CertiPUR US Certified, Queen https://www.amazon.com/dp/B07B9KDM5R/ref=cm_sw_r_apan_glt_fabc_3T8JF0SF0JE9VN6PTDKF