National Semiconductor has a line of switching power supply components called the "Simple Switcher" that take only a few components to make a low current power supply. The implementation cost on a PC board is certainly less than $28US. The simplest circuit configurations take the 8-pin chip, several low ESR capacitors, a diode and an inductor. See the following link for more information.

Do note that the use of switcher components requires careful design, component selection and attention to PC board layout technique.

http://www.national.com/news/item...40,00.html

Michael Karas