Hi, can anyone tell me where i can purchase a copy of flash professional 8

Not here. It's too far back for Adobe to sell.

You might find a copy on e-bay, but you take a risk buying software there, and even if the installer is valid, you'd need a valid product key or you'll only get 30 days out of it. Even ProDesignTools only goes as far back as CS3 with Flash.

Also, unless you're going to install it on a very old computer, I wouldn't expect much out of it.