For that price range, I'd suggest these two mATX cases that you may want to take a closer look at:
Cooler Master N200 ($46.25 @ Amazon)
Amazon Link:
https://www.amazon.com/dp/B00CUZP0SU/?tag=pcpapi-20
Manufacturer's Website: http://www.coolermaster.com/case/mini-tower/n200/
Best Features:
- Full mesh front panel (good for front intake airflow)
- Bottom-mounted PSU with intake filter (isolated PSU airflow, better case stability, and cable management)
- Up to 3x 3.5" HDDs and up to 4x 2.5" SSDs
- USB3.0 + USB2.0 front panel ports
- Can support a 240mm radiator at front
- 5x fan mounting slots (all 120mm-sized: 2x at front, 1x at top, 1x at rear, and 1x at side)
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Thermaltake Versa H15 ($43.45 @ Amazon)
Amazon Link:
https://www.amazon.com/dp/B01CLIZ698/?tag=pcpapi-20
Manufacturer's Website: http://www.thermaltake.com/products-model.aspx?id=C_000...
Best Features:
- Full mesh front panel (good for front intake airflow)
- Bottom-mounted PSU with intake filter (isolated PSU airflow, better case stability, and cable management)
- Up to 3x 3.5" HDDs and up to 3x 2.5" SSDs
- USB3.0 + USB2.0 front panel ports
- Can support a 240mm radiator at front and/or at top
- 5x fan mounting slots (all 120mm-sized: 2x at front, 2x at top, and 1x at rear)
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Most of the other mATX cases at that $40-50 price range have much limited airflow (solid front panel or partial vented front panels) and have top-mounted PSUs (not ideal in cable management and case stability and will also mean it'll intake warmer air inside your case to cool the PSU's components). So, for such a budget, you may just be limited into choosing the two suggested cases above, if you are looking for price/features.