The whole trailer towing experience should negate as many factors as possible for both comfort and safety. If you can stop sag with air bags, get them. Stop sway with a hitch bars, get them. And it's pretty much mandatory to get a weight distribution hitch if you are towing anything that's 50% or more of your vehicle's curb weight.
Now, can you tow without those 3? Absolutely. But just because you can, you definitely don't want to experience what can happen without them. Skipping out on a $200 difference in a better hitch setup is ludicrous when compared to your $50-100k investment in vehicle and trailer! I have the anti-sway in my Ram, but as others said, it will help correct it, not prevent it. I have an Equalizer hitch and it works great in the thousands of miles I have towed with it.
I saw a thread here where people don't understand how some of us can say "I don't even know it's back there". That's because we've done the homework and didn't cut corners. Do yourself a favor and get a hitch with anti-sway. Sites like etrailer are very knowledgeable and can steer you in the right direction. No pun intended.