Watch CW for their specials. We bought a new Hyundai, was going to buy the baseplates off net, but CW had a special install ($39) if I bought thru them. Anyhow rv came with the towbar just need the base plates. A set were about $150 less than CW, but to have them installed the min was $75/hr. So it was a no brainer to have CW install. Had them also install the light wiring for another $39 all together it was around $700. I installed the SMI brake system myself.
Look around for salvage yars or craigslist for used equipment. Buy a $1000 system for $150-200 (tow bar, or brake or whatever). There was a yard in yuma with a lot of listings for used baseplates etc on craigslist at one time. Never found anything I could use but there was a lot of stuff