I'm dismissing molecular biology kits

because I do not know what is inside
Qiagen workers making the secret recipe WITHOUT GLOVES! - Jeffrey/MacMillan for: Capital Business
I found myself using less and less kits dismissing some of them, because I don't know what is inside the bottle, so I don't know how to play protocol variations, I don't know how to optimize the assay, I don't know if I could afford them when I will have my small lab (they are pretty costly). Some more deep points are illustrated by Anna Git and David Piston in two recent Nature Comments, and I invite you to read the full text. Says Anna Git:
No self-respecting referee or journal would accept a research paper in which the authors relied on processes, substances or sequences that they had created themselves but did not describe in detail. Yet this is acceptable if those tools are purchased from a company. For the sake of science, everyone has to become more transparent.
Says David Piston:
Researchers, particularly those in training, use commercial or even lab-built automated tools inappropriately because they have never been taught the details about how they work. [...] As a result, they waste time by using a technique improperly or, equally tragically, miss something exciting when they assume that a strange result means that they did something wrong and they never follow it up.
So, here I am back cooking some Tricine buffer, the best one for luciferase. (At least, I wear gloves). Should a company develop and sell open-access kits, I'll probably buy them. I love kits as a concept. They are practical and save time. Making and storing buffers takes time (and space), I prefer having more time to read and think. Because I prefer making better science than spending my day around powders that do not dissolve and unstable pH-meters, or maybe because I'm a little lazy, which is good in science as far as your relentless curiosity dominates.