It's really something you need to experiment with until you find what works for you. Water type and individual needs can dictate what rinse works better than others for the individual person.
The BS and ACV are cheap and easy. Baking Soda should ALWAYS be followed with Apple Cider Vinegar rinses. These are pretty basic and will clean your hair/scalp without even lathering. For more effective treatments you can add essential oils, such a s Rosemary (which is good for dandruff) and/or Tea Tree (which will repel lice and mold.) The essential oils will be the more expensive aspects but to get started with just BS/ACV it can be as little as 5 bucks to as high as 10 (depending one where you shop - I've seen baking soda at the dollar store before.)
I tried the above but it just wasn't for me. I am going the Dr. Bronners route. Aside from ordering through their website you can find Bronners at Trader Joes or Whole Foods (among others.) Since it's diluted to a 1/12 it's strength it's pretty cost effective and I've had the same bottle this whole time (2.5 months) and I am nowhere near needing to replace it.
I dilute this into a squeeze bottle with a tip and add essential oils. The bottle helps aim the shampoo at my scalp and once I've applied it I will rub lightly with my fingertips. I don't always follow this up with anything but once/wk I do an ACV rinse. and if I plan on going somewhere and wanting my locks to really smell nice I put some of the dreadlock shampoo from Bucks County Soap on and rinse it out.
The Dreadlocks Shampoo that's advertised on this site is pretty good. I love the smells and it works well. I picked up a few bottles to try it out. I do like the Bronner's better for making my scalp feel clean though and will be sticking with that, using the dreadlocks shampoo for it's lovely smells. When my locks are mature I will try one of their bars to see how I like that as well.
A lot of people use only the shampoo and really love it. This is also something that would be applied to the scalp and rubbed lightly and then rinsed and not necessary to follow with anything.
It's all a matter of what works for you. Where the Knotty Boy is concerned, I've never used it and I don't know the ingredients so it's hard to say if this is good or bad.
ALSO you should be washing your scalp 2 - 3 times per week. The clean hair dreads faster because natural oils can prevent locking. After your dreads mature it's better to go once/week.