I use pirateship.com and I can mail 4 oz in a #000 bubble mailer for $4.52 using USPS' Ground Advantage service. You need to have a small, digital scale, which you can buy on eBay for cheap, to weigh your mailings and a printer to print a label. I just print them on a plain piece of paper, cut them to size, and tape them on the envelope. I use it for everything, not just chips, and I never have to stand in line at the Post Office, at least to mail something.