No, open source doesn't always mean free. Apple's OS X, for example, is based on FreeBSD -- an operating system that is derived from Unix and, much like Linux, is available for free. OS X, although based on open source code, is in no way free.
Regardless, those who consider open source software as being somehow inferior need to take a second look at what open source programs are available. And, yes, many of them are free. Linux is open source as are fantastic office suites such as OpenOffice.
The amount of quality software that is both open source and free may surprise someone who isn't familiar with how that concept has developed over the years.