Dave,
Nice idea. No idea about how much these cost you in time or resources to knock up, but if I was going for something like that for the A (which I might...) which was a "one-off" I'd probably go for around the £10-£20 mark dependent on size, quality of print, paper etc. If it was part of a larger print run then probably the £5-£10 mark.
As well as the Tintin style book cover which is good, another thought might be to expand the styles to include, say, Dan Dare/Eagle comic style and motor racing poster styles of the different ages.
See you at the ACE next tuesday to discuss further?
MG Mark