How do I get a key to gift from the Steam Store?

You dont get keys from the store. From what i know developers get tools to get keys so the only way to give away your game would be to buy it when you get a winner and send it over as a gift.

Steam Store doesn't give out keys for their games, you can only gift it directly to someone.

You can't. For keys shop at the third party outlets like Humble, Fanatical, Indiegala, etc.

very cheap bundle game, if u want to get a key
http://www.tremorgames.com/index.php?action=showitem&itemid=154266 (99 coins)
or use
https://www.steamtrades.com/

U cant save gift in inventory

Thanks for the responses!

If you want to gift it, then click on "Gift it". -.-