Item sells for $100. (as example)
You charge $17.45 actual postage.
That should leave you with $117.45
If you have funds held for 21 days, that $100 example is still on hold.
But PayPal took $3.79 out immediately for accepting payment (using this $100 sale example)
That leaves you short even with the eBay shipping rate discount.
The funds should come from your backup funds source.
Just a thought, but you can open a stamps.com account, which is free for eBay sellers (indicate that it is only for eBay use) and add postage to it. I've got that as a backup for when eBay shipping system goes down - which is rare but is has happened.
Other option, would be to contact PayPal and ask what the problem is. I believe you'll get a better answer from PayPal than eBay on this one since it appears to be a funding issue and that you can't mail via PayPal. You could call them using the link on the main page under "contact us". You have options for different issues, and receive a security code that is good for 30 minutes.
Good luck!
It is strange that the payment from the buyer isn't covering the postage, unless you're still getting the 21-day holds. If your money is normally available immediately, and all of a sudden is not, you do need to call Paypal. I have found their CSRs to be knowledgeable and helpful (in complete contrast to eBay's CSRs).
If your money is normally held for 21 days, then I think you need to get more money into your Paypal account somehow, by either asking a friend with a Paypal account to send you money, or by linking a credit card. (Transferring money from a checking account takes 5 business days, so that won't help you now.)
If you already have a credit card on file, has it expired recently? If that's the case, all you need to do is update the expiration date and you should be good to go.
You dont have the money in Paypal to pay for postage, and you dont have a funding source to pay for the postage. What happened to the money from selling your item? It should be in your Paypal account. If your label does not print out, try to print it again.
pay attention
I NEED HELP FAST! So I've been selling on ebay for awhile now and never had a problem with the printing the labels or paying for them. Just recently, I sold an item and the actual shipping cost was $17.45 but with the ebay discount it was 15.80. So under the "purchase postage" button, theres a box with a blue 'i' and in it says " Your shipping label amount is higher than the available funds for eBay funded labels. Please click "Purchase postage" to pay through your PayPal account instead." I clicked purchase postage like it says and now theres a new page with a red box that says "We're having trouble printing your label" and under it it says We had problem getting PayPal payment authorization. Please log into PayPal and update the funding source." I try printing it through paypal and the same thing happens. I didn't change my paypal information or anything. And please don't say call or email ebay or paypal. I need help right now