Man I feel your pain with the whistling. Cheap bars are the absolute worst for long road trips. I went through the same thing with my Traverse and tried a few different setups to find something that didn't drive me crazy.

• Chevrolet Traverse Roof Rack Cross Rail Package 84231368 OEM
• These are the most cost-effective. They fit the flush rails perfectly since they are genuine parts. They are solid, but the main con is they have fixed mounting points which kinda limits where you can put your cargo box.
• Thule WingBar Edge Roof Rack System for Flush Rails
• These are basically the gold standard for quiet. The aero shape really stops that whistling. They look sleek because they dont overhang, tho they are definitely at the top of your budget.
• Yakima JetStream Crossbars 60 inch Aluminum
• I run these now. They are super solid for heavy camping gear and bike racks. Bit of a puzzle to assemble the first time tho. Honestly, go for the Thule or Yakima. The peace and quiet is worth the extra cash for a ten hour drive.

Saw this earlier and had to chime in. @Reply #2 - good point! Thule is usually the go-to, but honestly, I was pretty disappointed with how their latest feet fit the Chevy flush rails. I had a set that just wouldnt sit right no matter how much I torqued them down. Here is what I have messed with over the years:

• Yakima JetStream Black 60 inch Crossbars with the SkyLine towers. These are solid but kind of a pain to get perfectly level on the Traverse roof line. They look great tho.
• Rhino-Rack Vortex StealthBar Black 2-Bar System. I tried these because they look sleek, but unfortunately the bar space is pretty limited because they sit between the rails. Not great if you want a massive cargo carrier and a bike rack at the same time. Honestly, even the high-end stuff can whistle if those rubber strips arent perfect... spent half a trip to the coast once taped up like a mummy just to stop a hum.

That whistling is the absolute worst, man. It honestly makes you want to drive the car into a lake after three hours of it. In my experience, if you want total peace of mind and zero noise, you really gotta look at the Thule setups. I have used a lot of different bars over the years and nothing beats the Thule WingBar Evo Black 135 for silence. They have this textured rubber strip on top that breaks up the wind... basically science magic so it doesnt whistle like a tea kettle. Since you have those flush rails, you will need the Thule Flush Rail Evo foot pack and the specific fit kit for the Traverse. It is gonna run you right at the top of your budget, maybe a bit more if you add locks, but they are solid as a rock. I am always paranoid about gear flying off the roof on the interstate but these things feel like they are part of the cars frame once they are torqued down. Definitely worth it for a long trek to the Smokies.