Well, from my experience, the best shopping is in Mazatlan; best prices, best selection.
But rugs and carpets? I've never thought of Mexico as a great place to get either. Jewelry, pottery, art, but not really a mecca for great rugs. Of course I've never shopped for any, so maybe somebody else can straighten me out. But even if you found a nice Spanish style area rug, the expense of shipping it home, or the hassle of lugging it yourself it seems to me would negate any price advantage.
You would probably do better at your local importer.