although I have not used it yet....I picked up
http://www.orsracksdirect.com/thule-672.html with the crossroads rail holders and I had the 48or50 inch load bars already. I trhink I got the corossroads and the carrier for like $650 including tax during a 30% off sale at REI or Eastern Mountain Sports, can't remember. Whatever you do I recommend you go to a store and see them first hand...I can tell you that the way the THULE evolution attaches to the rails is super easy and you can open from either side which is nice...Alos look at craigslist used stuff, sometimes you can get good deals on fairly new stuff. Yakima and Thule load bars are interchangeable with either system I was told.
Good luck.