Ever since discovering ball headpins, I haven't gone back. They add nice, subtle detail to earrings.
I used to regularly purchase them from Michaels, but since moving near NYC I've found stores that sell them in different lengths. The ones on the left, the $4.50 ones, are the bags I used to purchase but then I found them for $2.40 at a different store! No contest. (The $4.50 ones are from Bead Center.)