lol guys, well if you want to save yourself Ebay fees and the like, in bulk quantities, if its in good condition, and has some of the little people with it then its worth £8-£10 a kilo.
The old stuff isnt necessarily worth more then the more recent stuff, as the plastic was of a different quality and it often warps and loses its colour.
I've been collecting alot of the 1980's space stuff that was in the catalogues when I was kid that my parents couldnt afford to buy me - managed to pick up an LL928 (the big space cruiser) for £11, it was almost complete, but luckilly we had the parts to complete it.
My daughter is really into Duplo at the moment, have bought her loads for Christmas as its about the only thing she plays with

I really wanted the new VW Camper for Xmas that they've brought out, but its hard to justify spending £80 on it, no matter how nice it is.
cheers,
Claire