That might be difficult to prove, since RAF pilots wore the same leather helmets when flying all of their aircraft...Hurricanes, Lancasters, Mosquitos, as well as US supplied Wildcats, Hellcats, etc. And, you probably wrote "World War 1" by mistake, since your question actually refers to WWII.
$250 see ebay
It is worth what someone will pay for it - it's not a thing with a set value. If you list it on Ebay, the highest bid you get for it is another way of saying "that's what it's worth".
there not for sale there in musemes
You have what's known as a Hobo Nickel. The soldier design was carved into the coin after it left the mint. You would need an expert first-hand inspection to determine if you have a modern version (worth $5-$50) or an original (worth possibly hundreds of dollars).
The African American fighter pilots who fought in WWII are called the Tuskegee Airmen and they won more medals than any air unit in WWII. If you ever see the movie about them listed on TV it is well worth watching.
A world war 2 fighter pilots helmet can be worth the in region of about £50-£550 depending on whether it is British, American or German.
Easily $100+
If you think your head is worth protecing then a helmet is worth wearing.
$250 see ebay
Any guess is pure speculation.
It is worth what someone will pay for it - it's not a thing with a set value. If you list it on Ebay, the highest bid you get for it is another way of saying "that's what it's worth".
1000
The rose bowl helmet alone is worth 800.dollars a peace!
worth $250
95 dollars
500
there not for sale there in musemes