A couple of others have hit on it:
When the buy sends you the money and marks it as 'Gift', there will be no fee taken out. If the buyer marks it as for 'Goods/Services', then there will be a fee, because now it is a business transaction.
I have sold stuff here and received payment both ways. Since I *am* a small business, I don't mind that people do it as payment for goods. Either way, I have to report it as income.
I've also purchased things from here, and depending on the item have sent the payment both ways. In one case, it saved my butt that I sent it as 'Payment for Goods' because the seller disappeared with lots of people's money. I got mine back, but others who sent cash or had checks cashed, or didn't use the payment option in paypal lost a lot of money.
You can also set up a free account for yourself on the USPS website and print shipping labels there.