Hello micdarj_g.
Thank you for using Apple Support Communities. It sounds like you're getting prompted "cannot connect to iTunes Store" error message when trying to make a purchase. We can understand how this would be an issue. Allow us to investigate this issue and assist in any way we can. It also looks like you've already done a tremendous job in troubleshooting your specific issue. We'd like to share a helpful resource with you below:
If you can't connect to the App Store, iTunes Store, or other Apple services - Apple Support
This specific resource provides you with additional troubleshooting steps you can attempt. If these steps don't help resolve your issue, you might want to consider reach out to Apple Support for help. You'll see the contact link for them listed under "If you still can't connect".
We hope this information is useful. Best of luck.