Have you any idea how poor the monitors are with such a budget? No extra features, definetely no freesync compatibility, poor colours, very narrow viewing angle... with a budget like this you might as well stick with what you got because whatever new you'd buy won't be much better.
even 250$ for 1080p is barely something to work with. You can maybe get a full featured 21", but that's all.
You don't want just dize, you don't want just resolution, you want features too.