I donot think you can buy a brake setup for 100
when I bought a cheap core rotted sailboat for the trailer it was on
just replacing the hitch ball clamping parts was $95 on the brake headed part
Disc Brakes
$170.68 - $811.82
Drum Brakes
$151.70 - $967.95
that is just the trailer head controller not the actual brake parts
from
https://www.etrailer.com/dept-pg-Accessories_and_Parts-sf-Brake_Actuator.aspx