Thanks to Paula for this Frugal Baby Tip!
JoAnn's used to sell the classic Dritz diaper pins with the metal locking head. You might find them there.
As for being able to get diaper pins through the fabric, keep a bar of Ivory soap where you change the baby and keep the pins stuck in that until you are ready to use them. I have 3 pairs and they all stay in that soap. It helps the pins glide through the fabric. I use both traditional prefolds, stretch terry prefolds, and interlock fitteds. Those are by far the hardest but the soap makes it work.
Switch to a new bar of soap when the first is too full of holes to hold the pins. You'll be able to tell...the wrapper (keep it wrapped) will get so full of holes that the soap will dry out. I put my dry bar in the shower for my husband to use and I break out a new one. So far it's working great...My husband's bar gets used up just as I need a new one. What a system...