I like to pack buttons so that you are happy when they come in. If a few are bought, I card them, wrap in tissue, and then bubble wrap, and ship in a bubble envelope.(The bubble envelope may be recycled, but is still sturdy.)
I also roll up two sections of bubble wrap to put in the envelope, at either end. This way, the rolled ends are supporting weight on top of the package, not the wrapped buttons.
If a major amount is bought, I card, or package according to type. Plastic gets bagged. Glass always gets carded, and metal does most of the time. A large amount usually goes out in a sturdy box as well.
I like to see buttons come in well packed, so it's only fitting that they go out the same way.
My shipping prices cover the actual shipping price, confirmation delivery, and Paypal fees. I try to keep my prices as low as I can, so these things need to be covered. Thank you for your understanding.