Original. It is Canadian made by the Canadian Motor Lamp Co. (C L / C)
I personally would not buy just a shell.
value? since it's a bare shell, no liner , no chin strap
maybe $15 - $20 to use as a project or make a reenactor helmet, new repro liners are available
What Price Glory - UK MK II Helmet Liners
UK MK II Helmet Liners
New reproduction. Made to the same pattern as the original, but with modern materials that are more durable and will not stick to your hair. Complete liner including the rubber bumpers, upper padded cross, and brass attaching bolt/nut.