How come so many vortechs for sale?

I've never had a Tunze so I can't really compare but I think Vortechs are awesome and well worth the money. I could certainly never imagine going back to Koralia. They're like putting footballs in your display tank!
Like some of the others here though - I think I just got used to the noise. That, or maybe its because my living room (where my tank is) is so rarely anywhere near silent anyhow.