As a veteran shipper I've found that the good ol' U.S. Post Office is the best & cheapest there is for shipping EBay goods. It's Priority Mail sevice is cheap, fast & reliable in both price & delivery time. The benefits of Priority Mail are many. In the U.S. it has a 2-3 day guaranteed delivery time. Items under a pound are shipped for $4.80 anywhere in the U.S. If you are a conscientious EBay seller, Priority Mail is the way to go to satify customers and get good detailed feedback. Extra benefits include being able to tell a buyer who is returning goods to just right "RTS" or "Return to Sender" on the package & drop it back off at a Post Office. There is one caveat to this: the Post office doesn't like to see the Priorty Mail tape seals broken (evidence that the package is opened). So sellers should advice their customers to open the box on the back side by splitting the tape at the box seams & not disturbing the mailing label if possible. More Priority Mail tape over the old tape might also hide any evidence of the package being opened. Recently I split one right thru the label & taped it back so carefully with clear tape that it was difficult to detect without close inspection & RTSed it. If all else fails when RTSing a package, lie and say, "it must have been opened by the sender before it was sent" because nobody at the Post Office can refute that if you stick to it (I did this too). 

I routinely ship a specific camera model I sell on ebay all over the world. With the US Post office, it costs me a constant $12 to ship within the U.S. with delivery confirmation (which is needed  evidence for Paypal if the package is lost & you don't want to reimburse the buyer yourself) & insurance over $200. Internationally with the Priority service, it is $30-$35 anywhere with insurance of well over $200. But best of all, Priority Mail has  free (at least at my contract branch) flat rate boxes of different sizes that you can stuff as much poundage in as you can and still ship it for the same price as shipping a box of feathers. An 11X8 1/2X 5 1/2 flat rate Priority box is $9.80 domestic.

Contrast this with my experience with UPS shipping within the continental U.S.A.: I've paid anywhere from $12 to $16 for ground service (7-10 days) for the same package with a maximum $100 insurance! It all depends on how rural the delivery is. If it's being shipped to the boonies, UPS will hit you with a premium extra charge when it's being delivered out in the sticks because they don't go there every single day like the Post Office does. Once I sent a camera to Viet Nam for the same $32 with the P.O. as it is to Spain. UPS wanted to charge me $135 to ship it! Clearly the Post Office & Priority shipping is the best choice.