I have been buying my Escalon 6-in-1s directly from Escalon at its escalon.net site because it is the closest supply for me. But PennMac, chefswarehouse.com, Claro's Italian Markets (at claros.com), and several foodservice and cash-and-carry places, and specialty Italian markets also sell them. Some Kroger's also carry them, but none near me. Some places sell only the #10 cans. Some sell both #10 cans and the 28-oz. cans
If you are looking for a source for yourself, if you look under Resources, you will find a lot of threads directed to this topic.