A little late to the party but FWIW -
Bought a used (but nearly new appearing) ReadyBrute Elite off of Offerup for about 1/3 the new price, and it included the cover, safety cables, wiring harness for lights (didn't use), and 1/4 turn connection dogs (didn't use and are For Sale) used on newer base-plates (what attaches to the Jeep that the tow-bar connects to).
Found a BlueOx BX1120 base-plate on CraigsList for about 1/2 the new price.
Love the package as it doesn't depend on anything but the Jeeps inertia to invoke braking on the Jeep. The design allows braking consistent with what I apply in the motorhome (MH) that I pull the Jeep with.
I bought the magnetic light kit from Northern and a round 6 pin to flat 4 pin connector to interface the light kit to the MH.
Key to using this inertia system is getting it set up right - if you don't, you'll cook your brakes on the Jeep. The install kit that includes aircraft cable and sleeve that routes the cable between the front bumper of the Jeep, back thru the firewall and to the brake pedal is $69.00 thru Amazon. If your industrious, you can make your own for probably 1/3 that cost (10 feet of 1/8 SS unsheathed aircraft cable - front bumper to brake pedal, 6 feet of 1/8" SS sheathed aircraft cable - lever arm on ReadyBrute Elite to bobbin looped cable from Jeep at front bumper, a couple of cable bobbins, 2 1/8 to 3/32 aircraft cable clamps, and I used a beam clamp to attach the cable to the brake pedal arm.
All the above can be purchased from your local big box blue or orange store. The one kicker is - it is best that you use swage clamps to hold the loop (with bobbin) that attaches at the brake pedal. You don't want anything impeding the cable travel when the inertia arm on the tow-bar engages. Using clamps to hold that loop as it attaches to the cable could prevent the cable from being pulled through the sheath at the firewall underneath the brake pedal and as a result, no braking of the Jeep.
They both sell swages (cheap @ less than $2.00 a package), but the swage tool can run between $15 and $30 depending on where you source it. Swaging the loop is exactly what comes in the kit, and for my money, is probably the best/safest way to form that loop.
What I did was sneak around in my local blue box store, aircraft cable in hand - found swages, found the tool, looped and installed bobbin in cable loop with swage properly positioned and quickly used their tool on the shelf to compress the swage in two places. YMMV.
I may try to post pictures shortly of my whole set-up. Heading out tomorrow to travel west so will be a good time to get pictures of my whole setup.