As a bride who does have a couple things that are pricy (a kitchen aid mixer, down comforter) I would expect, if people so desired, that friends could go in on a gift together. The past two weddings I've been to, that's what my group of friends has done. That way, the couple gets what they want, and everyone spends what they can.
That's why it's called a registry. It's simply a wish list, and you are not required to buy anything from it. That said, it is bad manners to not have things in all price ranges listed.