I went for a eBay 4u server case, no hotswap bays or anything, just 13 or so 3.5" slots with a a row of 3x120mm fans behind them. Sits in the garage out of sight all for £45 delivered.
My issues are that I live in an apartment, so size, heat, and noise are large considerations, and that I want hotswap drive bays. What chassis did you get for £45? Does it use an ATX PSU or something else? What are the drive temps? Always under 30°C? 35°C? 40°C?
This one https://www.logic-case.com/products/rackmount-chassis/4u/4u-standard-chassis-15-x-35-hdd-sc-415h/ Got the price wrong it was £50, and 15 drive bays, I populate every other one. Temps are about 25 at the moment, but it is sat in the garage, which is always cooler than the house. I think I just run it with the 120mm fans (and CPU and PSU) but quieter ones as the ones that came with it sounded like an aircraft taking off.
