$6.99 plus $4.65 for shipping? That is insane!
Check the key section of your hardware store. The most expensive I've seen is $3.99, which is still WAY less than they are trying to sell them for here.
I was just at my local hardware store (McLendon's for you Washington State dwellers) and got a nickel dogleash style clip for $1.21. It is exactly the size that is used on the Coach Charms. I also got a brass one for $3.99.