The most consistent advice was to purchase a thermal label printer. They are fast, easy, and the labels are much cheaper than wasting toner in a laser printer. I got a lightly used Zebra ZP450 off ebay. Even though it was designed for UPS, it readily prints labels for USPS or FedEx. The 4x6 labels have enough room for customs declarations on international shipments. I even got it working on my Linux computer!
Here was the real find though, Shippo. Shippo is a shipping API for organizing, buying, and printing shipping labels. They have a straightforward web-based interface or you can work the API into your website using a variety of scripting languages.
Unlike Endicia, you pay per shipment rather than a monthly subscription. You also get to take advantage of heavy commercial shipping discounts. Even after the nominal 5 cent Shippo fee, it is still going to be much cheaper than the post office, upwards of 50% cheaper in many cases. If you have a Kickstarter campaign or if you just have a package to send to your grandkids, check out Shippo.
