If your into eBay, and your business is growing, than you should be automating as much of the process as possible. One o fthe great built in features of PayPal is automated postage printing.
But, to really use this feature to the max you need to print directly to labels. Although you may already be using standard size sticky paper for this purpose, you are not maximizing your profit because you are most likely printing with an inkjet printer.
Time to get a label printer caveman!
Take a look through your options.