I think you'll find almost all goods are priced differently in the UK, France, Germany and Bulgaria. Haven't you noticed this before. Do you never leave the UK?
Nobody was arguing that, Andrew. The argument was about being able to go to another country and buy the good, without (I think) import duty, taxes, or restriction - thanks to the European single market.
...
A more useful counter to 42's comment would be to say that: Yes, you have the right to go to a more distant ASDA and buy your groceries. However, that ASDA have no obligation to *deliver* groceries to your particular address.
Comparatively, you have the right to go to Estonia to watch Estonian football, but the Estonian broadcasters can decide (via contractual relationships with suppliers) not to *deliver* the content to you in the UK, Belgium, etc.
So the question is more like: should cheese makers (blessed be they) be allowed to contractually prevent Morrisons from providing home-delivery of their cheeses outside of the UK? Or "L'Asda" outside of France? Or Teskyyäää outside of Finland?