Flea markets may be good places to get Mexican cheese, but it's also hard to beat Carniceria Jimenez for all things Hispanic -- including imported Oaxacan Quesillo -- the traditional, hand-wound string cheese. If you haven't been to Carniceria Jimenez, you owe yourself a visit -- great place to get just about anything you can imagine needing, from dozens and dozens of dried chiles to bags of masa to cuts of meat you just don't find at Jewel to naranja agria to yuca and banana leaves, and on and on.
As for a Oaxacan meal, I think the two best Oaxacan moles are coloradito and chichilo. Garnachas are a fun appetizer, as are tlayudas. Tamales de elote tierno con queso y cream are simply dandy. Tasajo is a cut of beef indigenous to Oaxaca, and I've had it several ways -- from simply grilled to rolled with mushrooms, onions, and epazote -- and all were delicious. Oaxacan chorizo is sensational. And molitos are good, too.
Buen provecho. (And does responding constitute an rsvp, or does that need to be separate?)