I discovered this many years ago.

Do you know that a lot of newspapers houses (print) will let you have the newspaper ends for free.  That's the ends without printing on them, so no black marks on your hands.  They're thin, so you have to wrap multiple layers, but it's free and with a waterproof layer and enough tape it works just fine. 

Also, brown paper rolls from the paint section of home improvement stores work great. This paper is THICK and you get a whole lot of it cheap (unlike some of the brown paper sold specifically for wrapping packages).

I have a friend who works for American greetings and he gave me a bunch of decorated computer stationary. Since I very rarely use it, I've been using it to wrap, it's colorful and it was free.

I have been reusing the envelopes that samples from Walmart.com and Pantene and Dove come in. I just turn them inside out, put a bit if plastic wrap on the book, and tape the envelope to fit snuggly around the book. They are that shiny, coated, heavy paper, and most are the perfect size for a paperback or even a small Hardcover, and they too are free.

Cool, I love free stuff!

Paperbags from the supermarket work great also.  Just reverse them.

Be careful with paper bags from the store if they have writing on them. I remember reading a thread here about ink coming off on the books if you did not wrap in plastic first. Apparently the plastic bags from the grocery store do NOT leave ink, just the paper bags.

Allie

I use wrapping paper that I get for a dollar a roll at the Dollar Tree. I also have manilla envelopes that I use.

I have 2 giant rolls of kids painting paper.  My daughter doesn't use it much anymore so I just used that to send off my first book orders.