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.
Kings Toys 1 6 WWII RAF British Pilot Type C Flying Helmet
$21.71 (9 Bids)
Time Remaining: 5h 54m
WWII British Brodie Steel Helmet in Green
Time Remaining: 13d 8h 55m
Buy It Now for only: $74.00
SILVER SHOWA EMPEROR MEDAL JAPANESE WAR EMPEROR IMPERIAL WW2 ARMY RARE ANTIQUE
$6.50 (6 Bids)
Time Remaining: 2d 10h 7m
WWII British Brodie DOUGHBOY Steel Helmet dated 1940 Brown
Time Remaining: 3d 6h 25m
Original WWII British Brodie Helmet
Time Remaining: 4d 4h 40m
WWII British Soldier in Prussian Helmet Keeps Watch on Rhine Orig Press Photo
Time Remaining: 29d 22h 20m
Buy It Now for only: $28.99
WWII British MK2 Helmet dated 1940like US Doughboy
Time Remaining: 4d 5h 40m
Vtg 30s IMPERIAL JAPANESE FIREFIGHTER BADGE JAPAN MEDAL FIRE CHIEF FIREMAN WW2
Time Remaining: 4d 9h 22m
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