Asus make some really nice low latency gaming monitors. Personally I would stay clear of the Alienware stuff as you really are paying extra for the name, though they are good quality they come at a premium price. Asus are a good brand too so you won't go wrong with either.
As others have said though most computer stores online and even physical shops will usually give you a cheap option to have it assembled for you from the parts you selected, if you are willing to do the research and like to end up with quality rig and save some money that is the way to go.







