Most of the online merchants are expensive IMO. Personally I would apply for a trade account at your local plumbing merchants.
Personally I have tried all the brands for price & performance. Pound per meter I would recommend the Hep2OŽ barrier pipe. Very good and well worth the money.
Generally if you get a good trade account then there is no difference between buying 5 fittings or 50 fitting.... the price per item is the same.
Any other questions... please feel free to ask.
Hope that helps
