Hi brass,
I’m not sure why it would be better unless you are absolutely committed to memory foam in terms of your preferences and you’ve left out what may be the best options of all in your budget range … either a higher quality polyfoam mattress or futon or a basic innerspring mattress that uses good quality comfort layers that won’t break down or soften too quickly and that is a good match for you in terms of PPP.
If you were adventurous and in the lowest budget ranges and your springs are still in good condition (which is likely) then it may even be worth considering mattress surgery (see here) and replacing the foam layers in your mattress with higher quality more durable foam which should last you several years until you are able to buy a better quality mattress.
Phoenix