Depends on what you mean by "good". You can get a 27" or 32" 1440p monitor with passable HDR, but if you want 120Hz you need to stick to the native 1440p support instead of sending a 4K signal and downsampling it (which looks better, so that's definitely the way to go for games that only do 4K60). Sony's implementation of VRR is so limited that you won't get that on anything remotely close to "cheap" either. Especially compared to what you can get by just buying a TV.
Rtings' pick for lower mid-range:
LG 27GP850-B Review (usually $325-360 at Amazon, never buy a monitor from a 3rd party that ships direct as you'll get fucked if there's any dead pixels)
The 32" version of that is about $400-420, which could make for a better deal on Black Friday, etc.