Yes, I would like like to echo that. My problem was that Photos (2.0) gave the “Store unavailable” mistake and “Print Product Store Account” was greyed out. Apple support took me thtough the following steps:
Make sure payment info is correct
1.1 Open itunes
1.2 Click Account -> View My Account
1.3 Check if region matches region in Photos -> Preferences -> Print Product Store
1.4 Check Payment info
1.5 Open App Store
1.6 Buy something for free and install (if that works, payment info is correct)
Note: in my case App Store had different Apple ID than Itunes, changed that, did not solve the issue though
2. Delete certain cookies in the system
2.1 Boot in safe mode
2.1.1 Shut down Mac
2.1.2 Start holding down Shift key (at least until Apple logo appears)
2.1.3 Login screen should show “Safe Boot” in red in top right corner
2.2 Open Terminal
2.2.1 Terminal can be found in Finder Application -> Utilities -> Terminal
2.2.2 OR you can try spotlight search
Note: My MacBook Pro 2015 (MacOS 10.12.6)
2.3 Copy the following command
rm -rf ~/Library/Containers/com.apple.Photos/Data/Library/Cookies
2.4 Paste into terminal (if command-v does not work, try Edit -> Paste)
2.5 Open Photos, see if you can order, if yes, do it now
2.6 Restart normally, issue was fixed for me
My thanks go to the German Apple support and Tamerlan in particular.
Final Note: Obviously, this is just my experience, and things can go wrong when doing stuff in Terminal, so use at your own risk.