We have 485 units of the Arduino Stackable Header Kit in stock at our Sydney warehouse.
Arduino Stackable Header Kit
SparkFun's Description of the Arduino Stackable Header Kit
These headers are made to work with the Arduino Main Board, Arduino Pro, and the Arduino Mega. They are the perfect height for clearing the USB-B connector and great for stacking multiple shields. This kit includes 4 headers (2 8-pin and 2 6-pin), enough to connect a shield to an Arduino Main Board. These are the same headers we use in our tutorials and with our own shields.
Note: If you have a board that uses the Arduino R3 architecture which include the OREF, SCL, and SDA pins they can be found here. We know that many boards still do not use the R3 layout so we like keeping this kit available for those situations!