The wait is over! You can now purchase Marketplace.tf gift cards straight from Marketplace.tf itself.
After your purchase goes through, your gift cards will be credited to your account, and you will receive a notification informing you of this. To find your gift card codes, visit your gift card page. Here you can view all of your purchased and activated gift cards, as well as track when they're activated. This is also where your recipient can activate their gift card.
That's it! It's pretty simple and easy to use. Happy belated holidays!