The gem to find at the El Mercado are Day of the Dead sculpted dolls. Even then you must decide which are of good quality and which are overpriced cheap tourist traps. Look for ones that include symbolism and propaganda. For a small one, expect to pay about $30 and for a large one about $50 at the most, anything else is overpriced junk that is being exploited from the artist that they paid half of what they are charging.
Don't even bother with the Farmer's Market if you are wanting authentic Mexican merchandise, they are more like a flea market complete with Chinese retaurants. Definitely not the atmosphere the original Mercado is struggling to maintain.
