I would definately look locally for a custom box company. We have one up here I used for golf clubs and they had plenty to choose from and usually you can get them delivered next day. Only problem is you'll need to order in bulk like ~25 piece bundles. That way you won't deal with shipping or taxes(yes your tax form is required). Checkout uline.com
I actually bought some sunglasses and they came in a small form cardboard box that fit perfectly. you might want to invest in some rigid generic glasses cases to further prevent damage, especially if you're selling some high end oakley's or something.