Affordable shopping in Mexico City for younger people?

I'm returning to Mexico City for a week with a group of three friends in our mid-twenties. We're looking for affordable shopping options, particularly thrifting and antiques. We've already planned to visit La Lagunilla, but we're open to other recommendations for non-Sunday excursions. We're also interested in food and bar/club/venue recommendations that fit our alt/rock/indie tastes, but we're open to other genres as well. We're looking for a low-key club experience rather than a huge nightclub vibe. Additionally, we'd appreciate any suggestions for day and night activities, as we've already planned to visit the Frida Kahlo house and the Anthropology museum.