Title pretty much says it all.
I bought my Raspberry Pi a couple days ago and all the stuff I needed (or so I thought) arrived today. I was having some issues with the external USB hard drive not working for some reason. Some googling later, I find out that I need a powered USB hub.
So, what's the cheapest one available from Amazon (an item with Prime shipping)? I don't care if it's USB 2.0 or 3.0. My RPi is already being powered with a dedicated wall outlet.