Dawn R.
Yelp
First off, I'll say that this place is HUGE. Couple that with the fact that it's just a block or so from Le Merced, you're going to have a full day just visiting both locations. While I didn't really find anything that peaked my interest enough to buy it, a friend opted to get a "washing", which was entertaining to watch, and she then bought some items to help improve her love live and finances. We'll see if either are effective!
You'll also find a section selling live animals...everything from chickens and other birds to kittens, dogs, pigs, rodents.......I didn't ask the purpose, didn't want to know. Mingled in with all the mystical items are some regular vendors selling various souvenir items, books, party supplies, toys, school supplies, and pretty much anything else you can think of. Keep in mind that these markets are not there to be tourist attractions, they're where the locals actually go to trade. So you'll see a lot of things like fresh vegetables, raw meat, herbs, cooking utensils, etc. But if you have any interest in this culture at all, it's a must see on your trip to Mexico City.