The #1 place to look on the net for this sort of information is ; -

http://www.german-helmets.com/

Pricing, as ever, is difficult to fix - 'it's worth what someone is prepared to pay for it' - but originals in fair condition seem to sell over here for anything from £75.00-£200.00. If it's poor with no liner, then £30-50 is more the mark.

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"Stand by to pull me out of the seat if I get hit" - Guy Gibson