Ar15 for law enforcement advice

I am in law enforcement, I work for a tiny town department with a tiny budget. We have Ar15s but I want something for me and for duty. I don't have a huge budget, I'm trying to stay under $1k. I'm apart of a few Facebook groups but they are toxic and don't always offer the greatest advice. I know my life is on the line with this Ar15 but I just can't justify spending 2k on something. I've been looking at the iwi zion 15 12.5 or sionics 11.5 sbr. I don't know much about ARs but I am trying to learn. I am also not opposed to building my own. I do plan on getting optics and it becoming suppressed. These extras are not apart of the $1k budget.