New monitor

So I am a pretty general gamer, I like to play a lot of competitive games with my friends but also a fair few single player games. I sometimes find myself needing a map or some sort of list on the side for single player games and sometimes I would like a youtube video or something while playing other stuff. I was wondering if I should buy some shitty monitor for like 20 bucks just so I can have it on the side or should I buy an upgrade to my current one and use it on the side instead.

It is also helpful for you to know that I am on a budget of probably 250 bucks AUD max and thats a good chunk of what I have saved so I'm probably leaning towards the cheaper option.