there are some threads on this already.
Thule now has a kit availabile, go to their website and use their fit guide. The fit kit for the Niro rail bars is KIT4076. I live in Ottawa Canada so my pricing will be different from US pricing. I already had existing bars, locks from previous cars. They are super-easy to install .. takes about 5 minutes to put them on and less than that to take them off (took me a bit longer when I used them this week to go pick up my bikes from the shop .. my hands kept getting a bit cold!). Ive used them with a luggage box on top of the car, and I've had 3 bikes (Thule bike racks) on top. I use a small 2-step ladder that folder to help me lift bikes onto the top of the Niro. Very pleased with them