The funds come from the amount you received. If you use your PayPal Account to generate either a UPS or USPS shipping label, the cost of that label is automatically deducted from your PayPal Account balance.
When a customer purchases an item from you, PayPal will automatically deduct their fees from the amount paid and deposit the remaining balance into your Account. Then if you use your PayPal Account to generate either a UPS or USPS shipping label, the cost of that label is automatically deducted from your PayPal Account balance. The remaining balance is yours to do with what you want.
Regards,
skier
