The same thing happened to me with some stamps. I asked someone before I bid if she would combine shipping so I went ahead and bought all her stamps since the shipping would be affordable, thinking it would all fit in a flat rate box.
we completely misunderstood each other and she tried to charge me a fortune in shipping all the stamps (Stampin Up). They hardly weighed anything. I politely and assertively raised a little stink and she worked with me, but wasn't happy about it.
Try to work with the seller before you pay. That "ain't" right.