I think I'll get a few of those 4 channel chips. They might be nice to have around and are a bit more expensive here at the US suppliers. I was unsure of the cap size too, so it's good to know about that. I will go with a smaller one. I am also unsure about the 3k resistor in the output? The original DC to DC board has one. I asked Stan above, but he hasn't been back by yet.
The PCBs are still a bit pricey at OSHPark too. I cobbled together a single channel through-hole version and it was a bit over $4 for 3 PCBs. Might be able to shrink it up a little more? I might try a 4 channel SMT version to see how much that would be?
As Stan said earlier, it sure looks like buying the ready made board for $2 and swapping chips is going to be a lot less costly than making one from scratch. Of course it won't be nearly as much fun doing it that way. 
