the Britishicon Brodie style helmet in the first photo is the most collectable of the two, since it has the CD insignia and the helmet is more like a military type steel helmet worth about $20

the second one with the huge dome is the most common type and the least valuable, I had some of these and could NOT even give them away, they arent even worth the cost of shipping, maybe worth $5 at the swap meet.

maybe you could use it for bullet penetration tests? just for fun, to see how well it holds up to shotgun blasts or small handgun fire.