The "target" 1x1 brick is indeed printed, and there's only one per set– the dog's other side is a regular eye brick
If you're looking for them in-store, they weren't by the registers with all the other gift cards. I found mine on random holiday-themed endcaps throughout the store. I saw them in cosmetics, greeting cards, and by shoes; I'm sure they're elsewhere.
Despite what the post on FatWallet says, keep in mind that the Target website
(and my store's customer service, when I asked) states the minimum gift card amount is $5, not $1. You may luck out if you have an easily-persuaded cashier, but don't count on it.