In Mérida there are tons of shops selling Mayan rugs and blankets, silver, and other tourist objects; there are lots of treasures to be found among the loot here. Even more interesting things (from honey to piñatas to wooden toys) can be found at the Zócalo, with its mass of vendor stalls.
For those looking for a blast of modernism, there's a great shop at 428 Calle 60 (between Calles 47 and 49) called Vintage. Run by Maria José Cetina Cachón with a personable attention to detail, it's a treasure of vintage clothes, furniture, home furnishings, and other decorative objects. The shop is full of Americana and its Mexican equivalent (Mexicana?)—down to reformatted matchbooks from vanquished mid-century spots on the North American landscape.
To anyone who loves such mid- to late-century shops, the inventory here will be familiar; what sets this shop apart is its variety of carefully-chosen items as well as the range of Mexican objects on sale. I snapped up a rusted Orange Crush sign, advertising a Tienda "San Lorenzo." It's truly gorgeous, and was cheap by US mid-century furniture store standards, to boot, at 550 pesos ($50).