I have the transistors, already on the heat sinks (from IBM) and the LM317s are pennies each in quantity. I bought 20 a while ago. I got a bunch of 270 ohm resistors too at the same time so it makes a pretty cheap regulator. Most of the ones I have made are 3vDC, straight off the 317, to eliminate all of the batteries in stuff I have around here. If you run them off of a 5v wall wart the 317 never even gets warm. I seem to have collected a box of those wall warts over the years.
USB A cords are handy too since that is the output of a lot of these wall warts, (lighter plug adapters etc)
