Take a look on ebay and see whats out there, general rule the better the tool the higher the price.
https://www.ebay.co.uk/b/Brake-Flaring-Tools/82537/bn_60794340
Also take a look at Halfords what they have should cope with copper and knufer alloy pipe.
Practice makes perfect when using these tools, a dab of brake grease on the end of the pipe also assists when forming the flare.