I spent a lot of time on the Royal Mile learning about tartans. You can explore a museum, see how they are made, learn a whole lot about them and certainly buy lot of samples. In the United States, we might refer to the fabric as plaid but that doesn't mean the same thing in Scotland. Your kilt is a tartan. Your plaid is a kilt accessory that you might sling over your shoulder or use as a bedspread. So, technically, I searched for a plaid or a scarf but not a kilt. However, I was picky. I didn't care what my plaid looked like. I wanted my plaid to be from one, and only one, of the Scottish clans, the Martins. There were magnets and key chains available. Yes, I purchased them, but I really wanted the fabric.
In every store I searched, clerks readily agreed there was a Martin clan. Alas, nobody had any of the fabric. Upon research, the closest clans affiliated with the Martins were the Camerons and the MacDonalds. I didn't go all the way to Scotland to get anything from MacDonalds, no matter how they spelled it.
As interesting as all of this is, none of it is where I tell anyone to go to first when they visit Edinburgh, Scotland. If you want my favorite spot in the city, stroll on down Princes Street until you get to 120. This gets my vote as the most beautiful Starbucks in the whole world. (Number two is in Cusco, Peru) This caffeine café is in a beautiful art deco building that overlooks the Princes Gardens and the Edinburgh Castle through beveled glass windows. There's no finer view in all of Scotland with or without caffeine.