on Paypal DC is free on Priority packages. $.19 on all other packages. Please note you can only print postage for First Class Parcels, not FC envelopes or letters. The USPS website can tell you the difference. Of course you can also print postage for Media Mail, Parcel post, and Priority.
When you get a payment from someone, Paypal will tell you when it is "OK to ship". An E-check takes longer to clear.