IMO this helmet was either of 3 possiblilities starting with the worst (and most probable):
1/ Camouflaged way after the war which would make it a fake, at least when it comes to its camo.
2/ Camouflged right after the war either in Germany or on the way home by the vet who captured it which would still make it a fake
3/ Camouflaged during the war which would've made it against regulations anyway since, and please correct me if I'm wrong, multi-colored headgear camouflage wasn't instaured before the Stahlhelm--I actually read somewhere that it came as a result of a directive issued by the Chief of the General Staff of the Field Army Erich Ludendorff in July 1918--2 years after the pickelhauben were discontinued. Besides, pickelhaubes had their own mono-colored cloth camouflage covers before the Stahlhelm era.
Whatever this helmet was/is, it is IMO not worth more than $50 just for kicks.