Actually, there is nothing wrong with the 280x. He just isn't getting the right one. The reason why the Sapphire is more expensive is because of the game bundle that it goes along with. Check this out:
http://pcpartpicker.com/part/asus-video-card-r9280xdc2t3gd5
This is an Asus. Very reliable and it is about $80 cheaper than the 280x you picked out.
As for your power supply, you most likely will never need an 850W one. I would settle comfortably with a 750W.
Your case could be cheaper, look at this to get an idea that price doesn't mean the it will look awesome:
http://pcpartpicker.com/part/corsair-case-200r
Since you are building a desktop, would a wireless card serve much of a purpose? Might I suggest just buying a 100ft Ethernet cable instead? They're relatively cheap, around $10 or so.
And also, sound cards don't make sound "better". So I am positive that you won't hear a difference between having on and not having on. The onboard sound is amazing in itself.