Hang on there.
If all you're looking to do is drive a USB spinner and a bunch of buttons, then NO, you won't need a powered USB hub.
I can't do a schematic here, but here's the idea
Computer wired to a...
Hub (non powered) connected to....
USB Spinner
a Ipac2 or Ipac4 (probably just a 2 in your case)
Alternately, get a USB gamepad with enough buttons on it and hack the buttons (there's lots of info on here about doing that).
A single spinner and controller or IPAC won't overload the 500ma available on a single USB port, so you should be fine.
Just keep in mind, if you start adding things, esp led's, you can quickly go over 500ma (and realistically, you can't to stay well BELOW 500ma because that's the max and some equipment doesn't like being driven that hard.
But, from what it sounds like you want to do, it's all perfectly doable with a single USB and no power.