If you use PayPal or eBay shipping to print and pay for the shipping label, the actual cost of the shipping label will be released from your pending PayPal balance shortly after purchase. My shipping costs were released about 3 minutes after the shipping label was purchased.
If you don't have an available balance at the time you print the shipping label, PayPal will take the funds from your linked bank account, and then... release the actual shipping cost from your pending balance. This will make those released funds available for your next shipping label, unless you withdraw those funds.
When my payments were being held, I found it best to keep my PayPal available balance sufficient to pay for all subsequent shipping costs.
