There's never a long ass line, which is good, since I usually just want to leave my stuff and get moving. Much faster than the US postal service.
Prices are moderate- I sent a huge box to Japan for only around 30$, and they got it there FAST.
They even make keys here and have a really nice selection of them. PO boxes might be a little pricey though, and so might be some of their packaging products. But hey, it's a small business, so just pack your own stuff.
They also do cards and prints here too.