you can get packaging materials for super cheap if you order them in bulk online. I ship A LOT of stuff so it's totally worth it for me. Not sure how worthwhile it would be for a casual seller/trader though.
In three years I've actually never paid for any shipping materials. Everything I've ever used has come from either Amazon Prime, eBay, or trades with LRG members. I keep a stash of boxes and packing materials in my basement and re-use them (within reason) when I need to send something. Sometimes I've had to get creative and cut down boxes, but overall it's been sustainable.
The only exception is the poster tubes for international shipping, since the free-for-the-taking priority tubes would be too expensive to send out of the country.
Edited by bachamn, 09 June 2015 - 05:48 AM.