Here is a good way. Go to the moving store and get a big roll of shrink/cling wrap. It's heavy duty if you wrap it a few times, and also a very good way to preserve from dust and scratches.
Hang them from the garage ceiling. Or, you can get a shelf system that attaches to the ceiling, install it, then store them there.
Or how about letting another child use them for a while until you need them again?
Add your voice to the conversation. Click here to answer this question.