PayPal's fee is generally 30 cents plus 2.9%. You can read more here: https://www.paypal.com/us/selfhelp/article/what-are-the-fees-for-paypal-accounts...
I recommend trying to get people to pay more than a dollar, since the 30 cents is a huge percent of that. PayPal's fee is applied per transaction and has no effect on payouts.