I was aware of them but for discussion that's a good point. In my case I have a used yakima ski rack that I bought for $40. I'm going to fab some brackets so I can just bolt it on. The biggest cost will be the nuts and bolts at that point.Rhino Rack makes a cross bar for just that purpose.
These bars allow fitment of Rhino-Rack accessories such as luggage boxes and kayak carriers to your Pioneer System.www.rhinorack.com