tire noise

[X-WingYaris]

2015 Yaris LE
bought certified used March 2016 with 16k on the odometer and 1 year 1 month later it has 29k miles on it.



Only mod done to car is the TRD rear sway bar. It was put on with a torque wrench at the exact measurements.
About 3-4 months afterwards I noticed their was some noise coming from my rear tires. It was when I was hitting 20-50 mph I can really hear it. It was a low hum/droning noise and is constant. I think the tires were worn down on the inside more than the out. I think.
I bought new tires because they had become worn down.
After the new tires were put on and an alignment, the shop said the rear tires were out of alignment and they did the best they could to get them aligned but stated I needed a camber kit. I did not do the camber kit that day and they advised me to get frequent tire rotations. They are free from that shop since I bought the tires from them. I drove away and the noise coming from the rear tires was still there even with brand new tires. I had them rotated after 1500 miles in March 2017 and went back earlier this April to do the camber kit but every time I go to that shop its at least a 2 hour wait and me working 12 hour night shifts...I gotta get sleep. So I did not get the camber kit work done.
I told one of my trusted friends who is a mechanic and worked at a tire shop about it and he said it sounded more like a wheel bearing issue. The noise however seems like it is coming from both sides and doesnt get any louder or quieter when I turn. I listened to some wheel bearing issue videos on youtube and it doesnt sound like the ones I watched. I am not discrediting him or that that wheel bearing the issue but not everything adds up.
I am one of those that wants to get the problem solved the first time and would like some input from you guys about what it could possibly be? I am tight on funds so getting the camber kit done and then if that doesnt work paying for wheel bearing service does not appeal to me. I would much rather take it to the shop and have them check it and fix it right there. Hopefully cost me nothing to check it but I doubt it. Any help is appreciated. I do want to take it to a shop and this is my weekend off but its Easter weekend and most things are closed.

Thanks and Happy Easter!