I use the Revvy X on my Cocker, which has eyes, and it only cost me about $35. It doesn't make any noise while it waits, because the board controls the motor with a signal from the eyes. A contant-agitation loader like the ones made be Extreme Rage, Viewloader, and Tippmann, spin all the time, which is the noise you hear. This helps with keeping the ammo free from feeding hangups and aligns the balls with the feed neck. These make the most noise, while loaders with eyes will only feed when they sense a feed rate faster than a certain value, which they then use to turn an agitator inside the hopper. As Coenen said, if your budget is $100 for a loader, you can do much better.
Treat your gun right...OR I WILL KILL YOU!
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Rocking drop-forwards like they're going out of style...oh, wait...
My join date doesn't show it, but I've been 'ballin' awhile...