I want to start collecting WWII uniform patches.  My goal is to make shadow boxes for the patches of the units I've personally served in, but with a historical flair.  How can I tell if a patch is original and not a reproduction?  Where are good places online to shop for said patches?

Most WWII patches can be found quite easily.  The usual tell-tale things to look for are a cut edge and white backing threads.  They also should not glow under a black light.  But there are exceptions to the rules.

Militaria shows are a good place to find patches along with DUI to go with whatever unit you want to display.

The more rare WWII variations and bullion patches are being faked quite a bit as are many WWI era patches.

You could also take a look at US Militaria Forum.  They have a section for patch collectors.

http://www.usmilitariaforum.com/forums/index.php?/forum/1447-shoulder-sleeve-insignia-patches/