This is PROBABLY why.
People, for some reason, wont spend more than $5 on an app/game in the app store. Some people wont even spend a single penny in the app store.
Why? Beats me.
So, putting software that costs hundreds of dollars in an app store where people wont pay much wouldnt be smart on Apple's side.
I believe they have it on their website and you can buy/download from there. Not 100% sure.
It's just funny how people will pay a ton of money for movies, games, ect. and as soon as they see an app cost $1, they act like its gonna make them go broke.