They only do gift cards for certain things like phones and tablets now.
In the past I think there were more options, but in their trade in events for the past year or two, you have to buy an item from the same category (ie. trade in a camera, buy a camera/camcorder) but with specific requirements (brand and price range). You have to be ready to buy right away, they don't give you a gift card.
I don't think they've done a TV trade in event in a while.