OK, so another thing about self-publishing your book, is that you're the one responsible for sending out promotional copies to potential reviewers.
I got my latest batch of books, and made plans to get mailer envelopes while running errands yesterday. Only we got a late start, and we had to go to several places to get everything done. By the time we stopped at the third place, it was already well past lunch time (for all of us) and heading into nap time (for the toddler). I was still dealing with the remnants of a cold, and I didn't have much stamina left - we had to get home, fed and napped, and SOON. I decided a compromise was in order - I had planned to drive to another shopping center to get "real" poly mailer bags, but I knew there was a Dollar Tree in the same plaza as stop #3, and Dollar Tree carries 6"x9" bubble mailer envelopes, 2 for $1. My 5"x8" book fits perfectly in those.
So after stop #3 we walked up to Dollar Tree. I reached for the bubble mailers, meaning to grab 4 packs so I wouldn't run out, when I saw something else. 3M postal mailing brown paper - a big roll for $1.
I bought the brown paper, brought it home, wrapped my books in a plastic shopping bag (to protect them from rain) and then wrapped them in the brown paper and packing tape, and addressed them.
It may be a tightwad-dy solution, but I still have lots of paper, and this solution only costs me about 5 cents a book instead of 50 cents.
At some point I will probably go ahead and try to appear professional, and buy the "real" shipping options... when the book sells so well that saving 45 cents seems silly! :)