The cheapest possible "sway control" is making sure your trailer is loaded properly, with 10 to 15% of the GVW as tongue weight. A properly built, properly loaded trailer hitched to a proper tow vehicle should NOT sway! If it does, find out why, and FIX IT!
THEN, if it makes you fell safer, get whatever "sway control" gadget you want.
A Weight Distributing hitch doe NOT "reduce the tongue weight on the hitch". If your trailer tongue weighs 500 lbs, you will have 500 lbs on the hitch with the spring bars connected. What the WD hitch does, is force some of the weight to be "distributed" to the front of the vehicle by pulling up on the back end of the vehicle. In fact, since WD hitches are so heavy, they ADD weight to the back of the vehicle!
I towed a 15 ft. camp trailer and later a 19 foot TT with a Ford E150 Club Wagon (passenger van) around the mountains of Wyoming and Montana with no sway control and no WD hitch.
However, when towing the 19 ft. TT with a Jeep Wagoneer I HAD to use the WD hitch to keep the back bumper off the ground, and the headlights out of the treetops. Interestingly, that is what the WD hitch was originally advertised to do many years ago!
However, I did have a flatbed cargo trailer that had a sway problem. There was no way to load that thing to keep it from swaying! It was very poorly designed homebuilt trailer. Well built, but built WRONG! I sold it, advising the buyer that the axles HAD to be cut loose and welded back in the proper position.-