First AR? Buy a complete factory rifle and shoot it. If you think it's something you really want to get into then build your second one.
You might not need special tools to put together a lower but you will for an upper. Also, if you ever decide to sell one you might not get much of your money back on a home-built rifle. Any time someone posts a home build on the ODT I always wonder about the parts listed.
My go-to recommendation will almost always be a Colt 6920 OEM1. You can pick them up right around $725 and ODT members have enough spare stocks and handguards lying around to hook you up. Iron sights will get you out to 200 yards (unless you have old eyes like mine).
I agree but iron sights will get you to 500, accurately.