I don't know how you can really decide that Dredd equals 40, other characters 30 etc.
Prices vary enormously between story, artist etc.
You're also paying for original art, not comics, and the artist can only sell it once, and should therefore achieve the best possible price for it.
If an artist asked for a particular price for a piece of work I'd nevevr haggle, if I can't afford it, I put it back.
I've bought thousands of pages over the years, and guess I probably have the largest collection of 2000ad art about.
I started collecting because few others rated the work (enough to buy it), and it worried me noone seemed to want to keep things together either,and it also made a great learning tool!
I lend a lot of stuff to museums,galleries and exhibitions as I want people to realise wht beautiful art is being produced under their very noses, and to give other aspiring pros a chance to see how others work.
So when you buy a pice of art, it's not just the paper you buy, bought the collected editted talent of that artist.
Great stuff art...
Happy collecting!
:-) R