Here's another place at ebay that is great for tags. I got Chloe's from them and with both sides engraved and an additional line, it was only $6.74 shipped. I put her name, my street address, phone number on the front, and on the back I put three lines: my cell number, her license number, and her avid chip number.
custom engraved pet id
Here's the tag I got for Chloe: