I don't know why, but I found myself looking at the Minty Boost today. It's been around for a very long time, but I noticed that it was all through-hole stuff. Even so, the layout is extremely compact, and I wondered for a moment whether one could do something similar with surface-mount components.
Long story short, I was able to recreate the Minty Boost design with surface mount components. The board I came up with was slightly larger than theirs, but I actually put a couple of #4 mounting holes in mine. Believe it or not, that accounts for a lot of the difference.
I started to price it out and noticed immediately that the boost converter they were using was a whopping $6. No wonder they are charging $20 for the kit!
Well, shoot, that just doesn't seem reasonable to me.
I immediately lit upon the NCP1402, which I had used with great success on a GPS reverse geocaching project a few months ago. The only problem with that was that it topped out at 200 mA, which isn't enough for the Minty Boost's 500 mA spec.
Well, that led me to the NCP1450, which is almost exactly like the 1402, but with an externalized MOSFET switch. Since the switch is external, there's no longer a current spec - you use however beefy a MOSFET you need. The NCP1450-5 and a NTGS3446 together are less than a third the cost of the LT1302 they're using. In fact, I could sell the "Micro Boost" on Tindie for $10 without a case (that's the board with all of the electronics assembled, plus a 2xAA battery holder), and I'm fairly sure it would fit in the $2 AdaFruit clone of the Altoids tin.
But would anyone want one? Can't you just buy these at Walgreens now?