PayPal fees (I only take PayPal) and prefer that my bidders use the "goods" option so have a record, packaging (I use bubble wrapped envelopes when I can), and must buy 8x13 envelopes when I can't, which I then wrap in a bubble priority envelope and put into the 8x13. I have damaged too many home-wrapped books to use that method. I ship first class if there is enough $ to do that after Paypal and shipping, media if not. I combine shipping. I have also lost PayPal fees to international shippers sending funds even though I don't ship internationally. We are very very strapped for $ because hubby's entire division took pay cuts during the recession and I lost my job. I can't afford even pennies out of pocket.