I used to be one of those people who bought the powdered gravy mixes thinking making biscuits and gravy from scratch would be to hard. My Father in Law actually showed me how to make this, it's more a process than a recipe. I know I say that a lot, but cooking is an art, it doesn't always turn out the same and I think that's part of the fun of cooking.
Brown your sausage in a large skillet. Mix in about 1 Tablespoon of flour for each serving of gravy your wanting to prepare. Mix the flour into the grease, creating a rue. Be sure to cook your rue for a few minutes, getting a light tan color. This adds so much flavor and gets out that raw flour taste. Also add some salt and pepper, a good few shakes.
Next add your milk. Remember you can always add more if it gets to thick, but you can't take it back out. Start with a cup or so stirring constantly. As it thickens, keep adding until it reaches your desired thickness.
Serve over freshly baked biscuits. I admit, these still come out of a can, but the "real" gravy makes it totally ok.