It takes me a minute or less per book to convert them. 8 books would be 8 minutes or less for $20+ difference. I don't know about you but I make less than $165 an hour, so that conversion is worth it for me
($20 difference for 8 minutes calculates to $165 for 60 minutes).
PS you can Kindle-ize your books without having a Kindle through Mobipocket, and then you can drag and drop those files to ProcessGroup's LRF converter... let's say another minute. So 16 minutes work while you watch TV for $20 savings.
PSS You don't need a connection to buy, download, transfer, and read your Kindle books.