I believe the crossbars should have come with the rails at delivery, otherwise what good is the rack?
I agree why put the rails on if your not going to throw in the cross bars. The Highlander has always come with and without rails, rails always come with cross bars but not on the 2010 RX350--now cross bars are a $259 option.
Roof rack CrossBars [28] $259 [29] $259 [29] http://www.lexus.com/models/RX/features/pricing.html