I was thinking of replacing my Glow worm boiler soon and found these at a good price, all you need is a fitter, seems like a good few on here would give you a price.
http://www.ebay.co.uk/itm/Glow-Worm-UltraCom2-30CXI-Combi-Boiler-Flue-Natural-Gas-LPG-10008854-/201401609505?hash=item2ee478ad21