How to see the booster pack gem cost for all the games that you own at once?

Solution 1:

Unfortunately, no such list exists anywhere within Steam itself.

However, this page on the Steam Trading Cards Wiki attempts to catalog a list of all the different Steam games which have trading cards, along with the gem values for their cards, emoticons/backgrounds, and booster packs. Obviously, this includes games other than the ones you own, so it's a bit of a trade-off rather than a definite improvement. The list is understandably incomplete, not the least because new games constantly need to be added, but it may or may not be helpful, depending on what exactly you're doing with it.