I've been reading reviews on the mattresses you can buy online from Walmart and Amazon that ship to your door step in a box. I'm down to a single mom income, and the mattress I have needs to go since it's uncomfortable and honestly, my ex is all over it. Petty, whatever. Reviews have been decent on the hybrid memory foam with inner coil mattresses. I'm curious if anyone here has bought one and what you think? For under $400 I can have a queen size which is all I need. Should I? Should I not?