I took a binding class when they first came out. The instructor gave each of us 2. her comment was to buy a package of 10 and share them with friends, 2 for each friend.
I know of those who use the 50 package but using 2-3 was always good enough for me.
I do have arthritis in my hands/fingers so pins aren't really an option. Before the Wonder Clips I did glue basting for my bindings and even put a written tute on the QB.