Crema mexicana is so easy to make that there is no reason to pay more for what will likely be an inferior product. You can heat the cream in a glass jar or bowl in the microwave, or on the stovetop, and the only other equipment you need is an inexpensive digital thermometer!
1 cup heavy whipping cream
2 tablespoons cultured buttermilk
Heat cream to 85 degrees. Stir in the buttermilk, cover with plastic wrap and leave at room temperature overnight, or up to 24 hours, then refrigerate for 8 hours.