Where can I buy cheap rosettastone?

Where can I buy cheap rosettastone?
I’ve heard this is a very useful and helpful language learning software,which you can learn english by yourself.And also its obtained 5 steps of course,like when you learn french,you can start from the very beginning.Simple words such as greetings and easy daily words.Also you can learn italian in this software,it wont be that hard than any other way of learning languages.If you want tolearn spanish,its the same step.But it’s said this software is very expensive,who can tell me where to buy the rosettastone cheaper?

My rosettastone story
I used to learn english by myself,but gradually I found it became very difficult,because I can be engaged into that environment.So when I choose my second language I found learn french is much more intersting.The only question is how could I learn it at home even when I’m not in school anymore.One day I got a good news from one of my friend who learn italian,she said she was using one incredible language software which is rosettastone.I wasnt so sure should I buy it or not so I asked one of my friend who is teaching spanish,she told me many of her students learn spanish at home using this software and its really fun.So now I bought one,my langage leanring journey is now begin.