Drugstore valentines? Pssh, why would you want to get the same cards every other kid is passing around on Valentine's Day when you can make your own?
This video shows how to origami a heart-shaped valentine, equipped with an arrow shot through the center of the heart. It's just the kind of valentine Cupid would use. You can mix up the paper colors to make each heart individual for whoever you're giving them to, if you've got more than one valentine, that is.