I too, were a bit mesmerized by the DNA20 chip, so I started looking at DNA20-based mods. Primarily the Cyborg and the Wizard Evolved...
I noticed quickly on the datasheet that the unit's lower limit is 4V, which if you took the nominal battery volts of 3.7V (under heavy load), it means only one thing, it's a boost converter and not a traditional buck/boost you find in other VV and VW (with the exception of the Kamry K200
)
So I then proceeded to design my own buck/boost converter and realized why they did a boost only. In order to achieve the size and complexity, I could not find a switcher small enough and had enough amperage to achieve the 20W spec...
However, I do commend them for their flex circuit with the OLED. Flex circuits ARE NOT cheap... Charging $50-ish per board is actually a good deal, anyone who has ever done PCB design and fabrication knows that in small quantities, a simple PCB can cost a hundred bucks or so per board, and that's just the board, it doesn't include the SMT house, flex boards, OLED screen (and the rest of items on the bill of material), testing.
That's just the cost of raw goods, factor in labor cost that was put into just designing the thing, and pretty soon, $50-ish per board is a drop in the bucket...
I am still a bit enticed in designing my own board though, maybe after I fiddle with some mechanical components (it's one thing to just design the electronics, the mechanical fabbing and how everything is put together is the bigger part).
That's why for those that say the Cyborg and even Wizard Evolved is overpriced, consider the raw initial investment that it took to even create prototype #1, and you'll see that their asking price isn't much... Sure, you can throw it in a box with parts from Digi-Key and Newark, but it's nowhere as elegant as the stuff we see from these metal tube-type DNA20 mods: Cyborg, Wizard Evolved, and El3V8tor (I really wish these guys didn't spell it with 'l33t' type spelling but hey, it's their creation
)