RPi Through Hole break Out Box component list
Prices quoted are for guidence only
Prices were gathered from the websites quoted circa JULY 2012
Bigger savings can be made by bulk purchacing and items like tinned wire and vero board resistors could be used for other projects.
The suppliers are not the only source and bulk price savings can be made by checking out E-Bay etc.
DIODE, ZENER, 1W, 3.3V, DO-41 (17 off)
WIRE, COPPER TINNED, 25SWG
You are unlikely to need more than a foot which would imply you would be able to complete about 400 projects with even the shortest reel however considering the amount required for the project most hardware stores carry a card of fuse wire which would do at a push.
RESISTOR, 330R, 0.25W, 5% (18 off)
HEADER, STRAIGHT, L/LATCH, 26WAY (1 off)
SOCKET, IDC, WITH STRAIN RELIEF, 26WAY (2 off)
RIBBON CABLE, 26WAY, PER METRE
The ribbon cable is a commonly used industry standard and the length required for each project vairies, this ribbon cable can be salvaged from Old PC IDE and Floppy drive cables.