I think the F50 is undervalued too, not like the overvalued Enzo. I think this overvaluation of the Enzo will also reassure Ferrari to price the car around current mid Enzo prices. and resales of those who dare to resell for profit will probably bank about 200-300 sterling.
Although I think both F50 and Enzo markets will change soon when the Enzo replacement is released onto the market. I think the Enzo will fall to a more realistic value as owners sell their cars to make space for the new car ( although I think a lot have already done so to make space for their 599gto, which are all about to hit the market when they know they are on the new list, like last year as people were making space for the GTO there was 34 Enzo's listed on one website although 6-7 were listed by guinea hunters - some one who tries to sell something already for sale, but hopes they can cut themselves in on a deal) .
Once the new cars are near the end of their production ,I think this is when the F50 will be seen as a great supercar that is the last of the true drivers car made which is unassisted by electronics keeping things in check.