I can't stand the limitations of the Contacts method of printing address labels. I don't want to waste a partial sheet if my selection doesn't come out even with the number of labels. I'd like to duplicate addresses which I use often to fill up the partial sheet. I like being creative with fonts, colors and even borders or images. Your ability to be creative with Contacts printing is severely limited.
I've used Pay&Play's Label Printer Pro software for years. I originally paid MUCH more for this program. It's extremely versitle. Design one label and you can copy it to the rest of the labels in the drop down menu with one click. Chose how many of whichever lablel you want to duplicate with a simple cut and paste to fill up the page.
I can vouch that it works perfectly with Mountain Lion, v 10.8.2.
Here's the link to their direct download from their website for $6.95:
http://www.payplaysoftware.com/download.html
Or you can look up Label Printer Pro 7 on the app store and pay $9.99.
No, I don't work for or have any ties to the company other than being a satisfied customer of a product which suits my needs perfectly.
Also check the iWork Community for freebies:
http://www.iworkcommunity.com/category/downloads/pages/labels