I need a new bed

My mattress has seen better days.. It's nearly four years old but I hate to give it up since it has the memoryfoam top, which is so comfy.  The mattress below is worn out.  (okay no wise cracks!)

Since new mattresses are so freaking expensive (the decent ones) should I consider getting a slightly less expensive futon?   Or will those mattresses wear out more quickly than the $800 dollar ones?

Morgan Spurlock's "30 Days"

The guy that made Super Size Me has a (not so) new series on FX channel called 30 Days.   His first episode involved he and his wife taking minimum wage jobs for a month, and surviving on nothing but that.  It was really interesting, and good tv.   Last week (I've yet to see this one) involved a minuteman and Mexican immigrant living together for a month.. supposedly this had a surprising outcome.

Next episode is all about that nasty thing Congress pays corporations to do, that is the act of outsourcing jobs.