I don't think PayPal charges anyone fees if the payment is marked as a gift, but they won't resolve any issues that come up (such as the sender not receiving the item). So if you're buying, it's best to check the box for "I'm paying for goods or services" rather than "I'm sending money to family or friends". When you're buying you never pay fees as far as I know. The receiver of the payment pays fees when the payment is for goods or services.
So from the seller's side, you can just give them your email address on file with paypal and have them send you money. You can also request money with a simple form or send an itemized invoice to their email address. Once you're logged into paypal, just click the 'Request Money' tab.