La Unión Tejalapam, Oaxaca
Even though La Unión Tejalapam is in the Etla Valley, the colectivos bound for it from the city do not leave from the usual sitio northeast of the Abastos market. Instead, look for one(MX$13), displaying La Unión on the front windows, at the far western end of Juarez Maza on the north side of the Abastos market. (See map.) You may have to wait awhile for one to show up. Note: This is the same sitio that white vans bound for San Pablo Huitzo and Santiago Suchilquitongo arrive and depart from.
Alternatively, buses (MX$10) depart infrequently from their designated parking spot on Juarez Maza, about 100 meters east of the colectivos. (See map.) Look for a bus parked there, displaying San Felipe Tejalapam and La Unión on the front window, or the small signs, displaying San Felipe Tejalapam, demarcating its location Again, you'll probably have to wait for a bus to show up, possibly even up to an hour.
Whether you're arriving by colectivo or bus, have the driver drop you off along them main road through town. From there, it's best not to try and find the homes of the families that carve the alebrijes yourself. The pueblo is spread out and there are no street signs to speak of. So flag down a three-wheeled mototaxi instead and bargain with the driver to charge you by the hour. A local driver will be invaluable, since he'll know the the pueblo's back streets intimately. Ask him to visit Martín Santiago first, he's probably the best well known, followed by the Lopez, Perez, and Santos families. Hiring a local driver is probably even better than paying for taxi from the city to drive you around, since a city-based taxi driver probably won't have any idea where to go once he's in the pueblo.
To return to the city, have the driver drop you off at the main road. From there, flag down any Central bound bus or colectivo. One should be along soon.