Weight distributing hitch trailer end ~$750 to 1000
Truck end depends on vehicle from $200 to 500 + install
I have Tekonsha Prodigy P2 Brake Controller - Proportional ~$130 and love them (in 2 vehicles)
Wiring on tow vehicle if not wired ~$150 and install brake controller
If buying new get them to throw it all in on the package
Note some of the newer vehicles have issues tapping off the rear brake lights.
I learned the hard way with my Ram 2500 no fuses in trailer turn signals it has some sort of "electronic protection" and it shut down while under warranty and the dealer had to reset the body control module the service tech said some times they don't reset and it is $750 to replace it.
I added 10 amp fuses to the circuit so it doesn't shut down again now that I am out of warranty.