What about Bibles and reference books. I know you read those and they are not normally inexpensive nor "read only once" type of books. If you had either of those kinds of books at Sony you might want to retrieve, liberate, and convert them. They tend to be expensive to replace and you can convert them to Kindle format.

I started out buying books at the Sony Bookstore before I switched to Kindle. And even after I switched to Kindle I still occasionally bought books from Sony when they were cheaper than Amazon or when Amazon did not carry them. I then converted them to Kindle format. I also have books on my Kindles that came from Nook, Kobo, Fictionwise, Microsoft, etc. Just because a bookstore goes out of business, or you switch formats, is no reason to throw away all the books you purchased from them.