Originally Posted by avid01
So the bottom line is if I can get a book in either MOBI or EPUB (to read on my Kindle) I'm better off with going with the EPUB then convert it to KF8/AZW3 than to load the MOBI on the Kindle, right?
Probably not, no. The majority of books in the Kindle bookstore are now KF8. It tends to be mainly the older ones which are Mobi-only, and the ePub versions of such books are unlikely to use any formatting that Mobi doesn't support.
I buy wherever's cheapest. Lots of books from Amazon, but I've just bought a load of ePubs from "BooksOnBoard" to take advantage of their Christmas sale.