Free - I have a set of four Yakima Railgrab towers I bought new in 2013. You would need to supply Yakima round bars and saddles to have a complete system, but if you are a club member on a budget, this can help you get started.  

Railgrabs are designed to attach to most vehicles with raised roof rails. Includes Allen wrench and original instructions for easy installation. Also includes unused small and large roof rail clamps, with medium clamps already installed, to adjust fit for nearly any raised roof rail