The eyebrow fenders are not common, but are not valuable.
They seem to have been used mostly on town sedans by one report, but that is not confirmed. The ones I have seen were associated with town sedans.
I know of someone with some and I thought they might have some added value so it checked around. It turns out they are rare, but not valuable. Since they really are not special and not required for any special car they do not have the desirability to increase their price. I am sure it would be different if they JS said they had to be used on certain cars for a certain period of time, but that is not the case as you can always just use regular fenders.
The few I have seen for sale seem to sell for what you would pay for the regular fenders in the same condition.