So, couple of options. If you can swing 135 bucks, you can get an R6. Unfortunately, all that R&D has to get paid for. If you want something that is ACTUALLY very quiet, with one of the lowest anechoic chamber decibel levels of any case on the market, 135 bucks seems fair. That does not mean it fits your budget though, and I fully get that. That's exactly why "I" did not buy one at the time.
So, option number 2. Get a Fractal Design Define S. It's practically the exact same case as the R5, except without a front drive cage, fan controller, extra front USB ports, or side panel locking mechanisms, for at much less than the R5.
PCPartPicker part list /
Price breakdown by merchant
Case: Fractal Design - Define S ATX Mid Tower Case ($86.57 @ Newegg)
Total: $86.57
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-11-16 01:54 EST-0500
If you want one with a window, you're still going to pay about 125 bucks. I'll tell you straight up though that the R5, R6 and Define S, WITH windows, are all about 10db louder than the ones without Windows. Mine has a window, and honestly the amount of noise it makes from three feet away is negligible.
The Corsair Carbide 400c is a pretty good case as well. Well worth the price and worth taking a look at.
And if you still decide to go with the Define C or the BeQuiet unit, I can't argue that those aren't decent cases as well. Any of these will not disappoint you. Obviously though, if this is something you are going to keep for a long time, like I do, it's always worth considering that with cases you usually kind of do get what you pay for and an extra 35 bucks doesn't seem like that much considering the jump in quality and features.