I have a book that has a fixed layout, so it's not really easy to transfer it to ePub format (no one can manage to do that). I'm thinking of selling it as a PDF.
Is it possible to sell it as a Kindle book if it's just a PDF file?
No, Amazon does not sell PDFs on their site. If you submit a PDF to them via KDP, it will be auto-converted to mobi format for sale to Kindles. (As an aside, the fact that no major retailers sell PDFs in their stores is my primary argument for not calling PDFs "ebooks").
I personally think that it's possible. When you upload your PDF file onto Amazon website, they do the conversion into the supported format for an eBook. And for Books, of course Createspace allows you to upload a PDF file and which is converted as Print. I have done that with eBooks ever since I found out that it was possible now a year.
Source : Selling PDF on Amazon