You can lookup the value free by going to http://www.beckett.com
It's a free service, but you need to become a member (which is free).
*Click on Price Guides towards the top of the screen.
*Key in your player's name.
*Rekey in the player's name and select the hockey section.
*If you know the brand and year, key that in as well.
Looks like the current Beckett high value of his 79-80 Topps card is $550.
Believe that beats out any of the cards in my collection (I think).