I am doing cord blood banking and also banking the cord itself, "tissue" banking. Cord blood is most effective against childhood blood-borne cancers and I have 2 cousins who had leukemia and non Hodgkins lymphoma. They are sisters, one died at 19 yrs old. We grew up on the well known toxic waste dump site in south Houston, TX just around the corner from each other and so I worry for my kids. It's only like $3,000 initially then a few hundred each year to keep it banked. For me, I feel it's worth it.
I would not. My daughter had to have a stem cell transplant and I asked if I should have stored hers and they said it would not have made a difference. The cancer was not in her bones yet so they were able to harvest them from her. They said if it had reached her bone they still would. It have been able to used any stored for her, They said she would have a better chance with sibling or a matching stranger.
After all that I decided that it was not worth what it cost if even in my situation she would not have been able to use them.