If you're unable to find Ardbeg locally, you could always try mail order (your own risk - the Post Office won't allow insurance on bottles).
This tiny shop in Bowmore, Islay, has the most amazing selection of single malts, not just from the Islay distilleries (they have Port Ellen which closed as a distillery years ago), but also mainland malts and blends, up to forty-year-old bottlings, etc, etc:-

http://www.islaywhiskyshop.com/

I have no connection to the shop - I came across it while visiting my brother when he worked on the island a couple of years ago.

Ross