Neither snow, nor rain, nor heat, nor night stays these couriers from the swift completion of their appointed rounds.

Many times I have a package to send and I want to know how much it is going to be before I get to the post office. I usually head to the post office's website. They have all the information that you would get at the window just without the line. Not only can you calculate shipping but there a lot of hidden extras on the site like free boxes and shipping supplies. You will have to send priority or expedited to take advantage of the service but it is great for selling on eBay. I should also mention an offshoot of the website and that is Stamps.com. You can order stamps and the like but the real feature here is the photostamp. You can upload a digital picture and have it put on official stamps. Many people are using for weddings and Bar mitzvahs and the like. Give it a try!