Bake one complete bag of frozen hashbrowns ($1. 87 at my Walmart) in oven on 450 for about 25-30 minutes.
Meanwhile brown a pound of breakfast sausage ($2 at Walmart) with some diced onion in a skillet, breaking it up into small pieces. Drain and set aside.
Scramble 18 eggs (just under $2) in butter. Break up into small pieces.
When hashbrowns are done, dump all three into a crockpot and set on low until ready to serve.
Warm up about 30-40 tortillas ($3-4) - this depends largely on how full the crowd fills them. At church*, there are usually about 30 tortillas missing. (When I take this to church, I put the filling in my 6 qt. crockpot and the tortillas wrapped in foil in my 4 qt. crockpot. I keep them both on low all during church and they are hot and ready to serve after service.)
Serve with hot sauce and shredded cheese. (I buy in bulk, so I estimate I spend less than $3 on this).
Serves about 30 breakfast tacos for a total of $12, or about $0.40 per taco.
* The last time I took this to church for our after worship meal, one of the teenage boys told me that these tacos were the reason he got up that morning.