You could always get them right from the source - Yongnuo's own eBay store - I have bought from them at least ten times with no issues.
@Bosman, make sure you have some cold-shoe adapters like a Frio as I just learned that the YN-622C's do not have a 1/4" female thread underneath to screw into a light stand so you will need some cold-shoes to secure them to an umbrella swivel spigot.
Thanks for the tip, it too bad it doesn't have a thread on the bottom as it is more secure that way. I do have a couple cold shoes for my stands so i am set. I also have pocket wizards plastic flash housing RF blocker, it should mount on the bottom of that. I like them for protection in case it takes a tumble. I have 2 stands that i created custom mounts for using velcro straps and screwing into my pelican case. If i only need one stand i just extend the flash stand while being mounted to the case. This works well because it packs up fast and i don't end up leaving it somewhere like i have done in the past. D: