Heat 1/2-inch of oil in a large, heavy-bottomed skillet over medium heat. Line a large plate with a paper towel set aside.
In a cake pan or pie plate, whisk together eggs and buttermilk. Add 1/2 teaspoon of salt and pepper.
Mix the flour, cornmeal, salt, pepper, garlic powder, onion powder, and cayenne pepper in another cake pan.
Add shrimp to the egg mixture and coat well. Add the shrimp to the flour a few times and coat thoroughly. Place on a clean plate while you bread the remaining shrimp.
Add shrimp to the skillet, making sure not to overcrowd the pan. Fry for 3 minutes, until crispy and golden brown. Drain on prepared plate. Continue until all shrimp is fried.