Keep in mind the following PayPal policy which prohibits surcharges...
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No surcharges
You agree that you will not impose a surcharge or any other fee for accepting PayPal as a payment method. You may charge a handling fee in connection with the sale of goods or services as long as the handling fee does not operate as a surcharge and is not higher than the handling fee you charge for non-PayPal transactions.
https://www.paypal.com/ga/webapps/mpp/ua/useragreement-full#accept-payment
So if one of your customer open a Dispute or a claim on PayPal, you will be in fault and you will lose the money.