3-4 channel stereo mixer suggestion?

I run my iMac, MacBook Pro, and TV through my stero and use input select to choose my device for output. But I'd like to listen to iTunes or TV and still hear alerts from the other computer so I'm looking for a CHEAP Stereo mixer.

Must have 3 to 4 channels and stereo. Should have volume for each channel plus main vol. Ideally it would also have mute buttons.

Something like this is harder to find than I thought!

Any suggestions?

smaller, cheaper mixers tend not to have mute/solo buttons to stay cost effective.

BEHRINGER: 302USB

behringer do a good range of mixers: this one has phono inputs, which are cheap to get adapters for mac computers.

http://www.behringer.com/EN/Products/502.aspx