It's hard to find anything that ain't crap. I would pay the extra money but it is seldom out there.
I have 3 attic fans in my house that go through the top of the roof. All 3 went out over 2 summers and one had wiring so weak around it, squirrels found their way in (that's another story for the Pied Piper.)
Got tired of climbing on top of the roof, removing shingles and putting another in place. Finally, after some digging and calling, a company sold some attic fans made in Germany. I shelled out the 3x the cost of the Chinese Home Lowes Depot crap and WOW!.....you could tell just looking at it how well it was made. That's been at least 4 years ago and those things are still churning and move some air.
Like ironchop said; obsolescence
https://www.youtube.com/watch?v=D56nut_9e8s