I've purchased many roof rack, hitch, and trailer parts from RackAttack.com and etrailer.com. Etrailer has great install videos for most of their products. Here's a link to the Thule Evo system (not Maverick specific, but same procedures):

   • etrailer | Thule WingBar Evo Crossbar...  

Purchased my Thule rack from RackAttack.com:

Thule Evo Wingbars 60"
Bare Roof Fit Kit 5286