As far as making your own, I think it comes down to what you are selling and shipping. If you are doing high end packs costing a few hundred dollars, it is my humble opinion (and I think many would agree) that saving some money and making your own boxes may not be your best bet. Now, if you are doing a bit more bargain/lower end pieces, making your own may be worth it.
I would check uline for supplies. Maybe see if you can setup a wholesale account. Ebay has crazy deals sometimes that don't even make sense how they sell and ship for so cheap and still make a profit. I would also check with your LFS. They get tons of shipments in and many times toss these boxes. You could toss them a few bucks possibly. The boxes will most likely be large though.
