That's why I made the assumption...

I wanted it stated early in the thread before anybody less informed started to think that you were talking about empeg USB!

It might be as easy to get a USB hub and multiple USB-serial dongles though. (I assume that would work)

A cursory search tells me that [url=http://www.keyspan.com/products/usb/USA49w/]Keyspan] make one for $150. I'm guessing that any 4-port models are going to >= $100