Goodwill currently has a bundle of 3 Nook Simple Touch ereaders available for a minimum bid of $10.99 ending on 4/3/2018.
https://www.shopgoodwill.com/Item/50873654
I bought a kobo ereader from goodwill for $6.99 however the shipping cost more than the reader. . . something to keep in mind. At least it's for a good cause.