i was just at a fish store near me and i saw one for sale. It was called a Black Peacock Mantis Shrimp, and was only $7. their website is www.aquatictech.com you would have to call and ask for it i doubt theyy posted it on there.
I currently have a O. Scyllarus (Peacock) mantis shrimp and it is the best "pet" i have ever owned. It like to interact with me and my feeding stick a lot. I have it currently in a 5g acrylic hex and it is aboput 3-4". Peacocks do not get as big as many of the spearer varietys. My tank is rather thin and it worries me to see it chip away at the acrylic so a thicker tank will likely be needed eventually. If you find one, grab it.
P.S. Great site, I am learning a lot about Cephlapods and enjoying all your posts.