Having purchased garden soil in costales from 4 different viveros in this area, my nomination for number one vivero goes to Vivero Bugambillas on the Melaque to Barra highway just before the Pemex gas station on the left hand side of the highway if you are driving towards Jaluco.
Angel, the owner and one man band at the vivero is a super nice guy and fortunately his English and my Spanish are about on par so I always have an interesting conversation when I stop in there. Angel has a wide variety of plants and in addition to selling the best soil that I have found is also now selling costales of compost prepared in Cihuatlan. Plant information is free. Angel at times brings in special orders, a friend of mine was able to order two coffee trees and received them very quickly.
Stop in and meet Angel, check out the plants, (they are beautiful) have a seat in the shade and take in the clorophyl.