What are the best ways to sterilize shoes for resale?

Say you want to setup a shop where people come sell their shoes and they can buy other second-hand shoes.

You want to make sure that customers aren’t passing foot diseases around. You don’t even want any odors to persist.

What do you do? What do you use?

I know of the existance of www.sterishoe.com. What else?

Many thanks for all you can do.

And by the way, if it helps you help me, the most of the proceedings of the explained shop, will go to put shoes in the feet of the shoeless poorest.

Thanks!