How do cheap mattresses differ from each other?

Not all cheap mattress dealers are reputable, so educate yourself before shopping for a discount mattress or wholesale mattresses. There have been a lot of improvements in cheap mattresses over the last decade, so unless you're buying from a really low-end dealer, one cheap mattress should last about as long as any other. One thing to keep in mind is that when a mattress starts to sag, it's not the coils that are giving out, it's the padding. So high-quality padding will mean a longer-lasting cheap bed mattress.