As you know, I'm a huge proponent for saving money, in the real world or virtual one. As an eBay seller, I'm always looking for ways to make my items more desirable to the buyer while not cutting down my bottom line. Saving money on shippping is the most basic of steps.
I use USPS First Class for many of he items I sell online, and today the rates went up. The new First Class rates can be found here, but without a calculator they can be confusing.
So let's just say that any package weighing 13 ounces can now be sent via First Class mail for $3.45 (including Delivery Confirmation fees). A 16 ounce package (with the electronic discount) sent Priority Mail goes for $4.80. Not a huge chunk of change, but a considerable savings. With smart packaging, you can usually package your item in a bubble envelope and lower the postal rate. (A box weighs more than an envelope).
Don't forget that Delivery Confirmation is de rigeur when you use USPS. It's the only way that PayPal will stand behind you if the customer says the package was never delivered - and the USPS confirms that it has.