I've noticed lately than if you are shipping by Priority Mail (probably Express as well), that you can go online to schedule a pickup and they don't charge. I think the small pickup charge you mentioned for parcel post or first class is only $12.50.
I only sell one or two items a week, and I still bring the packages to the post office myself -- I don't mind going there as long as I can just drop the box in the slot and don't have to stand in line. The way ebay has shipping, label printing, and insurance capabilities integrated into their system works really well.
Technically as long as you are shipping one priority package your carrier should pickup other mail classes like media mail with electronic posage for free. Some carriers won't do it but they are supposed to.