LG is leading the charge with big, cheap gaming displays, having recently unveiled a 32-inch 4K model for less than $500. If you're willing to settle for QHD resolution, you can do even better with another new 32-inch model, the 32QK500-W. It packs AMD's FreeSync with a 75 Hz refresh rate and 8 ms response time, making it a decent gaming monitor. On top of that, the 8-bit + FRC IPS panel offers excellent viewing angles and up to 1.07 billion colors, so it'll be good for streaming video, too. All of that should come at a price around $300, making it one of the cheaper 32-inch displays out there.
Resolution is limited to 2,560 x 1,440 resolution, but in exchange, you'll get higher gaming frame-rates than you can at 4K, depending on your graphics card. AMD FreeSync is supported over the HDMI port only, but the monitor comes with a DisplayPort, Mini DisplayPort and two HDMI inputs, along with a 3.5mm headphone connector.
The monitor features LG's reasonable stylish Edge-ArcLine stand that supports tilt adjustment only, but you can also mount it to a wall. It's not yet available in the US (LG said it's "coming soon,") but can be found in Japan for 34,800 yen. That means it should go on sale for around $300 in the US.