Can't stand our current mattress, need an affordable replacement

I am 6 foot 3 inches and 125 kg and my wife is 5 foot 5 inches and about 80 kg. Can you make us a comfortable affordable (aprox £1500) mattress? We both cant stand our current mattress and agree we now need to invest in a better mattress as we are not sleeping well. Thanks ever so much in advance for advice and our mattress.