Walk into your local pharmacy and ask them for a bag of 1/2 cc insulin syringes with the long needle (1/2"). A bag has 10 pins in it. You will need more than that, but i dont think they will sell you a box (100). Depends on the laws in your state, or sometimes its just up to the pharmacist.
Or, there are lots of places online you can buy them from. They are cheap online, and most places will ship to your door within a few days.