The polish paratrooper helmets are not worth to much, many of them were used by the East Germans my father sold one recently for probably around $25.00 on ebay, there are quite a few of these around right now
They are reported to be one of the best fitting and comfortable post war para helmets ever built.
On the norm they do not fetch a high price in the market place unless you can find them with original nets and scrim which seems to drive the price up some.
Always on the look out for WW II Canadian Helmets and Cam nets to add to my collection.
Found a Canadian Mk II Medics Helmet and yes I know they are about as rare as hens teeth !!!!!