Block PO based off Vendors country

I have a requirement to block PO's from being put in against Vendors on our banned country list.

The check would have to be purchasing org and material type specific.

Be something like this: (for example)

Purchase ORG Material Type From County

US RAW Canada (meaning for Purchase org "US'' and material tye "RAW'', PO for vendors in canda would be blocked)

US Finished Canada

I could block the vendors but that of course assumes they exist in the US purchase org and also this check wouldn't satisfy the material type check.

Can anyone think of another way to do this w/out development?