It's rare to see these pop up on eBay, but I noticed something different about these. They are the standard 4" diameter!
When Space Camp produced these originally, they undersized them at 3.5" for some reason. This made them look awkward when placed onto flightsuits and jackets alongside standard 4" patches.
The seller said he had these made since he could not find them in the gift shop when he went to camp. So, here's your chance to get one at the "correct" size!
I received mine already. Here is a photo comparison of the replica next to the erroneous original.