Thanks chids. I think we've found one. As it's a top bunk one, I don't think we will be using it for more than a few years either, because then we will be splitting it into 2 single beds when we've done the upstairs extension, so will then need a proper single mattress. We've found one for £99 that we're happy with, so now I'm ebaying like mad so we can pay for it, plus the new duvet and bedding that we will need!