I've been bowling off and on for over 20 years and always changed my ball surfaces manually (towel in one hand and flipping ball in other).  However, I have heard people in my leagues talking about how they adjust their balls to different grits from week to week.  I know they aren't going to pro shops to do this.  They obviously own a spinner.

Is it worth it?  The ones I saw are around $250.  Are they easy to use?  Would be cool to keep my balls the same exact grit polish week to week instead of paying pro shop $3-5 to get this done.

DISCUSS

your comment has nothing to do with the point I was making.

I just picked mine up yesterday. I got it as part of package deal with some other shop supplies for $175. I'm feeling pretty good about it!

Admitted bowling dork here, made my own spinner.
long story short, mine has adjustable speeds via frequency drive
Infinite speed adjustments available to me
I would suggest getting what you can afford
1/2 HP and 2 speed would be my suggestion (I don't see a real need for 3/4 HP)
I believe you have a choice of 450 0r 650 rpm
I like to use mine at 300 rpm for surface adjustments and maybe 500 or so for polishing.
thought is to keep the heat of the surface as much as possible (which I can do with water if need be)
I prefer dry sanding if I need a dull surface, say 1000 for a heavy pattern
Wet sanding and 1000 pad doesn't seem anywhere near the results I get with 1000 & dry
Some asymmetric balls don't like that higher speed on the spinner and vibrate quite a bit IMO

all in all - better investment than a new ball(s) - IMO anyways