If you would like to build your very own benchtop power supply you might be interested in a DIY tutorial for Supplino. A versatile compact Arduino power supply capable of providing from 4 to 40 ...

TK discusses a portable power supply module known as a Battery Shield for Raspberry Pi and Arduino.

Each of the power supply modules are two separate PCBs and the design has to account for the high currents required. The power supply is a switching design with some filtering on the motherboard.

The power supplies have overvoltage and overcurrent protection and an LED indicator. For ease of installation, each model can be mounted on a standard DIN rail. L-com’s new open-source Arduino PLCs ...

Another answer is to find a higher voltage supply and mate it with a cheap power supply module. We’ve also seen non-PC power supplies put in a PC case.