I haven't found them in my area either but I found a pretty good looking web site for Mexican food that's suppose to be low carb. They even have some recipes. I haven't ordered anything from them yet. They sell La Tiara taco shells. A case is 12 boxes (216 shells) for $26.75 or a box of 18 for $3.50. They have both kinds.

Here is the address: http://www.lowcarbtacoshells.com/recipes.shtml

I hope this helps and good luck!