As you can see it has a small 4 pin power connector. You don't have to use it as the riser itself is powered.
The one your looking at is probably a good choice.
I guess I can get this "adapter/riser thing" on e-bay right?
It's much better to get this adapter. you can run upto 4 devices from this one. I am using one with 4 cards plugged in. no additional power required by the adapter either. Just ensure you get the VER 002.