just created a book from iphoto, hit buy book

Apple does no offer any print services for iPhoto. The Print Product stores have been closed last year.

Save your book as a PDF file, then upload it to a service, that still will print Apple Books from PDF, for example Mimeo or Presto Photos.

See: Ordering Books and Calendars on a Mac that cannot be upgraded past El Capitan

• • Mimeo used to print for Apple and can handle PDFs created in Photos, see: https://import.mimeophotos.com
  • Also Presto Photo can print from Apple https://www.prestophoto.com
  • If you are not located in the US, there may be local printing services, which would be more economic with respect to international shipping fees and shipping time. In Germany we can use photographerbook to print existing Apple PDF files: https://www.w2p-photographerbook.de/fotobuch-aus-aperture-iphoto-fotos

To save your finished PDF book as a PDF file :(https://web.archive.org/web/20170614002828/https://support.apple.com/en-us/HT201504 or Check and review a project before you order using Photos on Mac - Apple Support)

If you're really using iPhoto and are able to create a PDF file for that book there's a 3rd party book provider which used to do the printing for Apple as a sub-contractor, Mimeo, that will take PDF files created by iPhoto and Photos and print and bind books and calendars. 

Also you can upload the PDF file to PrestoPhotos which can also print and bind books and calendars from iPhoto or Photos pdf files.  They've been doing it for some time now.

Use the PrestoPhotos or Mimeo links above for direct access to the PDF file uploading and book/calendar ordering page for each site. 

Apple ceased offering printing services 15 or 16 months ago. Make a pdf of the book and try a third party service, or one like this:

https://www.prestophoto.com/create/apple-photo-books