Hi
Does anyone know what the difference is between the cheap and expensive memory foam mattresses?
There are more than I can shake a stick at on Ebay for about £150 (kingsize),new. But then there are plenty in the £350 and £600 bracket. The ones on the John Lewis website are 1k+! 
We've got double one in the spare room from ebay which seems fine to me. But now 7 months pregnant with twins it's the only way I can get comfortable. So I'm looking for a kingsize one for our bed. I don't mind spending the money, but would rather not if there is no difference between them! 
TIA