Hi whickerman, As a rough guidline for you and it is really a "guestimate" without knowing the size of cylinder, whether it is a direct or indirect, and a vented or unvented system you get the picture . But expect to pay around �200 for a good quality Part L compliant cylinder + fittings and around �150 for labour depending on where you live that is.
I honestly didn't know there were such a range of shapes & sizes until i started looking into it last night. It looks like I'll need to get a man in...