winEQ is usable free, but you lose some of the functionality. It works fine for me, have been using it since 2001.
ISBoxer is the evolution of winEQ. It takes a bit to get set up just right, but it kicks ass for what it does. Afraid though that I do not use it myself so can not help with the particulars, just offering my opinion that yes, it is worth the cost, but you can lose hair getting it set up. Know a lot of folks who are more then happy with it, especially the instant switch+key repeaters.
Be patient and ask questions with plenty of information, folks will lend a hand =)