as above, if he's getting it himself he's probably will be making a bit ontop for it, which is how a painter makes his money

Last time i checked you were lookin at about £100-150 a panel

Tbh if u go sourcing the paint yourself you might find him getting funny about it, some paints do go on differently and he may want to use one he's used too to minimise any problems.

But if he's happy for you to source the paint you can get it cheaper than that mate!