I’ll borrow an answer from The Street.
The collectible market is a tricky one, and a lot of what people believe will be valuable winds up becoming completely worthless (remember that '90s Beanie Baby craze?). The sector evolves over time, and interests -- and generations -- change.
The basics of supply and demand. You unfortunately selected a collectible ...
You have a few options actually.
TCGPlayer: Will give you market price and median
Ebay : Will give you what people are asking for the cards
AlternativeWorld: Seems a bit outdated, but it may help.
Hope this helps.
Edit: Also I noted that in your question you referred to it as CCG (Collectible Card Game). If you do your searches with TCG (Trading Card ...