Just found this website that makes fixed and adjustable switch mode
regulators in a three pin package. The fixed output 5V is $12 and the
adjustable is $15. These should do the trick for almost any onboard flight
computer.

http://www.dimensionengineering.com/

They also sell accelerometers and have a simple design for making a digital
display for it. I think I just might make one for my ship!

Jim Vincent