Embargoed country list

[thisismicah]

Hi All,

I am working on an e-commerce project with a UK publisher selling digital content.  We have a requirement to prevent users from certain embargoed countries from adding to basket or checking out.  Pricing could be supressed based on a users account details or GEOIP location, but we also need to potentially block transactions during checkout (if a user were to enter a new address or edit an existing address, within the checkout tile).

Our general "modus operandi" on the project is to standardise wherever possible.  With that in mind does anyone know a standard way of maintaining a country specific "blacklist", and if so, how this could be used to supress pricing and prevent checkout?

Thank you in advance!

Micah