I'd like to say that I started making my own seasoning mixes because I have it that together. Not true. I am lazy and I really wanted tacos. But we were out of seasoning mix. Realizing that I own every spice under the sun I figured I could make my own. And I could! It was super simple and very tasty. Now in the grand scheme of things, you aren't going to save a lot of money by not buying seasoning packets, so I don't recommend going out and purchasing all of the spices to make them. But if you have them in your cupboard why not? And it's a lot healthier for you as well because there aren't a lot of processed ingredients.
Here is a link to my favorite taco seasoning mix from About.com.
Anyone else have some recommendations for tasty homemade spice mixes?