Gravitycers is not listed on the bundle contents section, but it's listed in the description of the pack (under the game images), therefore I assumed it's the bonus game.

PrinzVonBillAir is from EU.
Please check his thread again, it states:

You can pay in € and $ (PayPal only) or CSGO (no capsule or hydra) keys. If you pay in € or $ you have to cover any fees. My PayPal account is located in the EU.

Wait till Valve realizes that they sell 21 games for 1 dollar...

aaand for the 314699 sub anyways? what can we do for making a giveaway? =P

The 21 games pack can't be bought directly on the Steam Store, therefore you won't see it in the list when you try to create a giveaway.
You have two options:

1. write a ticket and ask the support team if it's possible to add it; it they added, you should be ale to get 3.15 CV for it
2. giveaway the whole pack as one of the included games; you'll get 0.15 CV (since any game costs $1)

There's no way of finding out if a key works or not, unless attempting to activate it. If the person who activates it has at least one game missing from the pack, the key will be used in the process.