Creating a giveaway question

Either. As long as you can gift the game to someone, it's fine.

So if you buy a ton of $0.01 HL1 games on a super sale, wait 3 weeks, and put up giveaways...that's cool :D

You can gift a title from Steam that you've not redeemed, either through old packs or gifts to your own e-mail address. Or buy the game specifically for the giveaway, but it need not be bought through Steam, games with Steamworks, like Civilization V and others can be bought through other means and the Key can be sent to the winner.

Extra copies also are fine.