By "supplies" do you mean just ingredients?
We go to a place called Minos Imported Foods for all of our Greek ingredients. They sell fresh feta out of the barrel, olives the same way, pita bread, tzatziki, all the good stuff.
I always bring cash, they do not take cards. They are tucked away in a loading dock, so you have to keep an eye out for their sign. Below is their information & Google maps information.
Minos Imported Foods Inc (704) 841-2806 11016 Monroe Rd Matthews, NC 28105.
"minos imported foods" +matthews - Google Maps