I think the prices suggested by Alec and Daz are pretty accurate.  The cost of the earlier sets has shot up quite significantly in the last 4 years or so and is indicative of the number of people now collecting these sets.  This is also borne out by the number of people bidding on Panini stickers at auction houses.  It used to be one man and his dog and is now every man and his dog.

The old theory of supply and demand means that I will always look for older sets at decent prices as they become more rare; anything for Euro 2000 or before. 

I think Ebay has been a contributing factor in saturating the market for the more recent sets as we all can see how much Panini stickers sell for and there are now so many more people chasing the same dollar.  Consequently i don't think the new sets will ever be rare enough to fetch decent prices. 

Regards,

Ian