James you can't count, your one liner is actually 2 lines :
never say ' we are more expensive.....'
say ' our prices maybe slightly higher than .....'
if you want to justify a higher price then use the time equation.
what i say is " we work as a 2 man team and will allow 3 hrs to clean your suite so that is 6 man hours, Quikyclean, Ultradri etc will work alone and will take 90mins, that's why they can charge £80, ok we are £40-£50 more than them but it allows us the time to do a thorough job, which we know you will be happy with"
a bit of a mouth full but once explained most people can see the sense behind it.
Mike
ps My best one liner is 'why don't you have a chat with your husband and get back to us' I say this on jobs that I don't want to do!!