I have seen buffalo wing sauce - but it's pretty hard to come by in some areas. I'd bring a bottle or two just to get you going, then look around for some, or learn to make your own.
Taco seasoning is dead easy to make yourself. Honestly. It's better that way, too, because you end up with less sodium and no MSG. Just mix chili powder, cumin, onion powder, garlic powder, a dash of salt, and a touch of cayenne pepper (however you like it) and you have taco seasoning. All those spices can be bought here.
Enchilada sauce can be made here, too. It's also very easy.
Biscuits you will have to learn to make yourself. You can't find them here.
Refried beans are everywhere, spicy or regular, and pretty good. Black beans seem to be found by others, but I have yet to find them in my area. They are a bit more difficult to find and you may have to go to several stores before you spot them. Soured cream is available here, it isn't exactly the same as what you get in the states, but it is ok. Just be sure to buy the stuff in the refrigerated section and not in the jar on the ambient shelf by the taco shells and stuff. Ewwww.
Veg nuggets and things are easy to find. I think there are actually more alternatives for vegetarians here.
Pecan pie is fine to make with golden syrup instead of corn syrup. I used a recipe from the BBC site last year and it came out just great. For pumpkin pie, I would suggest bringing a tin of canned pumpkin or whatever you need. It's very hard to find in some areas.
For Mexican food, I would consider bringing some tins of green chiles and/or Rotel, if you are into that. You won't find those here. Also, if you like to make "white man's queso" with Velveeta, I would suggest bringing some Velveeta with you, you won't find that here, either.