British war helmets from WWII are little cheaper than those of WWI according to my research on all completed sales on eBay on the last 90 days. WWII helmets are traded every single day with minimum of 10 bids, which means there are great number of engaged buyers and sellers. You can expect to pay anywhere between $50 - $300 for a helmet based on condition & rarity.
If you are looking to buy a British helmet, you will have to join the bidding war. For example, on September 12, 2010, a WWII British helmet was sold for $267.88 with 24 bids. Take a look at the helmet on the right. It is not in great shape, but still goes for high price because of its rarity.
eBay is indeed the best place for searching WWII British helmets for sale from various sellers and collectors. I don't think there's any other place like it. Below are some of the listing from eBay. Browse the the listing and click on a link which you are interested in. You will be taken to a page with more information on the helmet.
British WWII Helmet With Brown Netting
$9.95 (1 Bid)
Time Remaining: 1d 21h 54m
WWII British Brodie Steel Helmet in Green
Time Remaining: 16d 21h 9m
Buy It Now for only: $74.00
WW2 Canadian British Civilian Steel Helmet Zuckerman 1940
Time Remaining: 3d 9h 21m
Buy It Now for only: $60.00
Vintage English Bulldog Churchill Dog Metal Figurine England WWII British Helmet
$19.99 (1 Bid)
Time Remaining: 3d 10h 16m
WWII British Military Motorcycle Helmet
Time Remaining: 3d 10h 58m
KINGS Toys WWII British RAF Pilot Type C Flying Helmet
Time Remaining: 26d 12h 3m
Buy It Now for only: $27.95
Kings Toys 1 6 WWII RAF British Pilot Type C Flying Helmet
$20.71 (8 Bids)
Time Remaining: 3d 18h 8m
SILVER SHOWA EMPEROR MEDAL JAPANESE WAR EMPEROR IMPERIAL WW2 ARMY RARE ANTIQUE
$3.25 (4 Bids)
Time Remaining: 5d 22h 21m
Here is a list of previously sold British helmets on eBay. Use this as a guide so that you don't pay too much for a helmet in the future.
- Dispatch Rider Helmet 1945 - MINT : $200
- Paratrooper Helmet - REPRODUCTION : $157.50
- Tommy Helmet - 1942 - GOOD : $142.50
- Tommy Helmet - 1942 - GOOD : $79 (notice the difference in price. I checked the auctions and both are almost in same condition. If you shop, you can still buy the helmets for cheap)
- Motorcycle Helmet - 1945 - GOOD : $112.50