I made a batch of three powders and three liquids from recipes I found on tipnut (google laundry detergent tipnut). She has a list of ten recipes. I had the ingredients for six and decided to try all six in small batches (1 gallon - old vinegar bottles - for the liquid detergents and 3 cups - plastic containers given to me and we use glass - for the powder detergents). All of them work equally well!
I did not care for the mess and time #10 took to make and it is the most unusual consistency once done....too time-consuming all around for that one, for me. Otherwise, I would do any of them again. I wrote out the recipe on masking tape and put it on each container as I made them. I went through the powders faster than the liquids (lower quantity) and I haven't bothered making anymore of that. I don't care for powder detergent either, but it does work well, especially for sheets and towels. All the liquids have been awesome! I added essential oils to my recipes and it smells so much better than commercial detergents to me.
I love the self-sufficiency in making great smelling laundry detergent whenever I want. No waiting to do laundry or only doing the most important load because the detergent is running low. Whipping up a powder detergent is super fast and easy and I keep a jar of grated fels naptha ready to go. Making liquid takes a bit more effort, but is fun and satisfying.
Cost-wise, I am not sure homemade is all that much less expensive. Finding sale detergent can be faster and cheaper than finding washing soda. Even Borax was a bit challenging to find. We looked everywhere we went for 2-3 months before we found either one. Now, we know where to buy both (Ace Hardware for Washing Soda; Wal-mart for Borax) and both are special trips because we don't shop in either place regularly. Soap is more flexible and we have a local discount store that usually has a laundry soap for $1 (not always the same brand) and I generally go there once a month. If one were to stack coupons and play the grocery game, one could easily find commercial detergent for less money than retail price and possibly less than the ingredients for homemade....not to mention your time to make the detergent.
I don't think homemade is always cheaper and that isn't why I do it. I do it for the satisfaction of learning to do something "new" (to me) and for the knowledge of what is in the products I use (the assumption is it is healthier, but that is open for discussion/interpretation) and for the flexibility (I can customize things the way I would like them vs. buying what everyone else has) and I simply enjoy making things myself.
The way I look at it: You can buy lower quality for cheaper than homemade or you can pay less for a comparable product (maybe slightly better quality, depending on your criteria) if you make it yourself.