We DIY for many reasons. Some DIY because what they are looking for does not exist in the commercial products market (this used to be particularly true of the headphone market). Other DIYers start down the road of building their own equipment because they think they will trade blood, sweat, and tears for dollars saved over buying commercial. The latter group (of which your author is a member) sometimes touts the price to performance ratio of DIY as a reason that others should get into the hobby. But let’s get this straight: if your goal starting out is to save money on equipment, turn back now.
If you start down the DIY road, you will spend money making mistakes. You will spend money accumulating parts you will never use. You will spend money on tools that do not factor into the parts cost of your projects. You will spend money on projects that you decide do not fit your idea of listenable audio. Until you get really good at what you do, you will not recoup money by selling your projects. At the end of the day, it would not be accurate to say that DIY saves money. But do not let this discourage you! Money is not value; they may occasionally be interchangeable, but they are not equivalent.
When you pay money for high-end, high-dollar, boutique design, the value is in the performance. The performance is funded by the money the designer spent making mistakes and a lot of crappy products first. You are, in effect, paying for the time and experience it took for someone to become exceptional. The DIY pursuit requires having the courage and the patience to face mistakes and become exceptional yourself instead. The scope of this value far exceeds the performance of what you build.
For example, if someone told you they hiked to the summit of Mt Everest, you might think they are pretty amazing. If they told you that their first thought when they got to the top was how much money they had to spend on socks, you might start to wonder about their priorities. What is the price to performance ratio of the experience of climbing a mountain?
The price to performance ratio of DIY would be better phrased as the cost to value ratio. The costs of DIY, all things considered, are no lower than buying commercial, and the performance is not significantly better. The value, on the other hand, is in your own education and the rush of emotion when you hear music without smelling smoke for the first time. DIY is your trek to the peak of Maslow’s hierarchy. That is not something you can buy at the local hifi shop.