Don't mean to take anything away from sold (amazing product) but we are starting a company that takes care of the shipping, for anything. Check it out if interested http://shyp.co
It's a pain if you don't have boxes and tape and whatever, that's true -- looks like your service handles that for you which is pretty sweet.
Another huge thing people don't realize is box size. In most cases you can save up to 50% off the shipping price if you can fit your item in the tightest box possible. There are only a few sizes USPS provides for free using priority mail.
We have about 20 different box sizes to take advantage of this.