I have a 100 gbp budget for my monitor, I can either get a 75hz 21” 1080p monitor new or a 144hz 27” 1080p monitor used, is there anything I should look out for if I buy the used one, and should I buy it, and I will be able to view the monitor in person, this is my pc https://uk.pcpartpicker.com/list/hfFGYT