I have some purple kush I picked up at my dispensary. It's my 2nd favorite right now - right behind the orange kush I have. The PK I have looks similar so don't sweat whoever was telling you it wasn't. If it smells fruity then you've probably got the goods. Enjoy.

PS - Is $20/g a lot?? I pay $25/g (if i buy that small an amount) withouth thinking twice - this is at a dispensary of course.