ever seen the Black Eyed Peas perform live on tv shows like idol and dancing with the stars?
that's the antares autotune boxes doing their magic.
except on fergie who doesn't need one (although I recall one Idol appearance when they stupidly had it on her voice too and it was so awful LoL - she's an excellent singer but wasn't singing with the intention of being autotuned (in other words she was still using her typical wide vibrato and glisses and showy vocal runs which do NOT work with autotune boxes).... what a catastrophe that was.
but yea they come up on craigslist often for a couple hundred bucks. they're fun, although really only as an effect for live shows for that type of techno stuff.