I have a 14 and 11 year old. Bought two beds from Argos that came with mattresses, and are rubbish. Already the springs are coming through. So I'm wondering if anyone can recommend a mattress please? I'm sick of buying mattresses that don't last long. But nor do I have too much money. £250 per mattress is the max I can afford. I think memory foam might be better and won't have to worry about springs as much. Any recommendations?