Willing Your Frozen Eggs and Embryos to Your Kids?

With women of advanced maternal age having put off having their babies until late in life, I'm hearing more and more discussion about the fate of frozen eggs and embryos. I'm surprised that nobody's given the fate of these precious little bits of life some thought before now.

What happens to the frozen eggs if the mom never uses them? Are there any laws on the books for this situation? One discussion that I heard said that maybe they should be part of a person's legacy and left to their children. I can see where this might be a viable solution. What if something happened that your daughter's eggs were damaged and she couldn't have children? Having a few of mom's unfertilized eggs lying around could really simplify things (and reduce the cost of?) in case she needed to opt for in vitro fertilization. What is the shelf life of human frozen embryos anyway?

On the other hand, what if you have no children and the future of your fertilized or unfertilized eggs needs to be decided as part of your estate planning? What should be done? Is it ethical to just toss them? Are there facilities that welcome donations or do people sell them? Ethics aside, what is the price of frozen human embryos? I have to admit that I'm not knowledgeable in this area but I would love to know more about it and can see where there might be some controversy because of the disagreement of when life begins.