I use PayPal shipping for packages, but it is not available for letters. I have stayed away from Stamps.com for the reason most have cited (monthly fee). I try to keep an inventory of stamps for those letters. I routinely order them from the post office website; you pay an extra $2 now (used to be $1) as a convenience fee no matter how large the order. I have not waited in line at the post office to buy stamps in more than a decade.