Paypal charges a fee depending on which method you choose when paying someone.
When you pay someone, if you choose to pay through friends and family, you pay the fee (so you will have to pay extra if you choose this method).
If you choose to pay for goods and services, paypal will subtract some of the money you're sending to the other person for the fee (So the other party is technically paying the fee).
In most cases, artists have people pay through art via goods and services. I don't recommend paying for art via friend's and family because I don't think you get paypal protection when you choose that method and it makes it easier for people to cheat you of your money.