I use a lot of dry shampoo because I only wash my hair about once a week. It does get pretty greasy by the end, especially when I'm working out, or biking, or it's summer. So by the end of the week it's usually about 50% dry shampoo. I've tried Klorane since it came highly reviewed by every blogger and magazine and website, but to be honest it didn't seem anything special, and the bottle went super fast. I felt I only got a few uses out of it, and for the cost, it was not worth it.
I got a three-pack of these batiste dry shampoos at Ulta on sale. They have horrible scents, like "sassy and striking mamba." I have no idea what these smelled like besides artificial. However. They soak up oil like a boss and make my hair magically look clean and fluffy again, which is the job of dry shampoo. They also barely leave any white residue and I can just fluff and go rather than rubbing it in a lot and brushing. Despite being tiny, I feel like they lasted longer than the Klorane, and they were super cheap. Batiste in general is cheap and I would buy it again, in an unscented version.
Except, I've been using plain cornstarch and it actually works fine. It's much messier and takes longer to apply, and it doesn't make the hair as fluffy as an aerosol can of dry shampoo does, but it works. I either keep it in an Altoids tin, where I just put my fingers in there and pick some up sticking to my fingers, then work it into my hair and repeat and repeat, or in an old cleaned out spice container with the little holes so I can sprinkle it in my hair. But cornstarch is kinda clumpy and it tends to not come out and then dump a ton out. The cornstarch also tends to really need a lot so it builds up if you are using it a few days in a row. However it is basically free, and it's travel-friendly as it is not a liquid, gel or aerosol. The internet also suggests using arrowroot powder which I also purchased fairly recently, and might try out. I think the same issues would apply. Although it's cool to go DIY, save money, and reduce the waste and chemicals associated with aerosol and packaging, though they no longer destroy the ozone layer, sprays tend to work better for me. I'm still looking though, and might try the Bumble and bumble Prêt-à-Powder.
Another similar product I've tried is Sally Hershberger Caffeine for Major Body 3-in-1 Volumnizing Spray. I read this review and went to a bunch of shops until I found it at CVS. At first I really thought it was working, but recently I've noticed if I spray it on hair that maybe already had some dry shampoo in it, it leaves this horrible sticky white residue. So, I no longer recommend. Maybe it's best to add volume to clean hair but that's not why I need dry shampoo.
tl;dr Dry shampoo is a life-changer.