I think something small like Rock Miner did was pretty cool (the 100GH unit). Maybe make a pod like Bitmain...something that does not require a computer PSU to run.
The problem is that there may not be widely available high efficiency power bricks.
Competing with 70% efficiency bricks agains professional miners with 92% efficiency PSUs is hard.
look into, i think Delta's, laptop/desktop external PSUs, they hit the 87-90% but they are a higher voltage DC.
There is also nothing wrong with using a PCIe power adaptor off a desktop internal PSU
There is if the aim is a starter device. To us the idea of paperclip jumping an ATX PSU is second nature, to newbies it's daunting.