Ocean City had one last week, it's 5-6"...huge. I don't remember the price.

"peacock" is used as a catch all name for almost any mantis in stores because they have no idea what it is. peacock mantis is also he correct common name for O. scyllarus (a potential tank breaker who requires minimum 30g as an adult). G. chiragra is a smaller species but can also crack a tank as it has the hardest hit pound for pound for any mantis; also reclusive, not a very good pet. If you can get a pictue of the beastie you are thinking of buying, I may be able to ID the species for you.

yup.
Like I said, few and far between.
not impossible and not every type of mantis.
Very few are actually that strong.