Buy local is just the 'little brother' of buying national. I recall,years ago, while living in Australia, there was a full-blown government campaign urging everyone to buy Australian made goods. I always thought this was a strange way of thinking.
On the other hand, if I find a local shop or market which offers unique or better quality goods, then I would be happy to buy local, but there needs to be a valid reason to, not just because it's local.