For the look just get any ACM (All China Made) POS scope. I just have the red dot for the look to be honest.... Although that said I still do have my red dot co witnessed against my irons and kind of use it, kind of.
Also it depends on the look you want to achieve. If you want to build a Block I SOPMOD then build one up. What does that mean? Anything from an ACOG 4x scope (although you can get airsoft ACOG x1 scopes that look like x4's), KAC drop in RIS/RAS, KAC BUIS sights, Harris bipod. That's just one of the many things you could do to your gun, or you could even pick and choose things you think are cool. For example if you like the look of the Tango Down battle grip, who's to say that it's right or wrong.
What I suggest is looking in the media section here and online just to get an idea of what's available and what's out there for you because for the AR15 platform the sky is the limit, hell you could even pickup a "tactical 12oz. refreshing beverage holder" to attach onto the rail of your gun (those things actually exist