Help buying a copper pan
I have never sprung for copper pans, so this is just from my general research.  

Here are the factors I would look at:


How thick is the copper?  You want it to be thick enough to retain and distribute the heat of the burner.
How is the handle attached?  Rivets are better than welded for long term use.  (This is general to any metal pan.)
What is the handle made of?  Is it oven and broiler safe?
What is it lined with, and what care does it require?  Copper is too reactive to use for general purpose cooking unlined.   Tin will need to be replaced over time, but probably is not in use in modern manufacture.
What care or cleaning will it require?  


See also:
Navigating the different types of cookware - new kitchen advice