City of Villains goes for really cheap - $10 or less just about anywhere (I got the Collector's Edition at CompUSA for just $7). City of Heroes could be found for the same price, but it's a very old game, so your local retailer's not likely to have it. Amazon's your best bet for CoH at just over $10.
If you don't want the hassle of looking for them separately, buy the recently released Good vs. Evil Edition which includes both games and extra stuff, and retails for $29.99. I'm pretty sure you can buy the bonuses from NCSoft directly if you don't want to buy this edition, though.
I dunno about gift cards, because they're probably the worst gifts you can ever give someone. They require absolutely no thought and force the receiver to shop at a specific place, often at marked-up prices. The only time you should ever give one to someone is if you know that they would've shopped there anyway.
