I'm still on the hunt for a cheaper source but at least I know they are available. When I have time for a longer search I'll let you know what I found or if any of you find a great source for these milk bottles please let me know.
After seeing the cute little milk snowmen that I previously posted about I started a brief search to find milk bottles. I found these pictured above. They aren't cheap $150 for 24 but you can use them over and over again - just like any regular drinking glass.