I do not think region specific tags are necessary. The idea of the site isn't to put a user in contact with a retailer. It's to recommend a hardware product that meets their requirements. It is helpful to link to a retailer, but not necessary.
Both parties in a post should take care to provide relevant details about where they are located. My default assumption about a user's location is generally based on the currency they provide for their budget. If they provide a budget in dollars, I assume they are in the United States. If they provide Euros, I assume they are in Europe. If they provide another currency, then I assume they are in a location that uses that currency. If someone is asking a question and provides a currency and a location that don't match (ie. dollars and they are traveling to Europe), then I assume the explicitly mentioned location.
While a link to a retailer is not necessary, it does make an answer "better". Along the same line of reasoning, a link to a local retailer (or localized online merchant) is probably better than a link to a global merchant, simply due to pricing.
Tags for regions, though, are not useful. They are too broad (ie. "United States", "Europe", "Asia"), because of the huge geographic differences, tax laws, supply in specific regions, or even different countries in the region. Alternatively, they can become to focused (ie. "Chicago", "London", "Seoul"), in which case they are useless because a product available in Chicago is probably available in Detroit. The same is true with London and Paris or Seoul and Tokyo.
As someone who wants to provide recommendations, you simply need to provide a recommendation that is helpful. If you know a product is hard to get in a certain region, make a note of that.