I looked at "Honey I washed my Hair"
http://www.lushusa.com/hair/shampoo-bars/honey-i-washed-my-hair/05563.html
The main ingredient and syndet cleanser in the bar is sodium lauryl sulfate (SLS). They have also included small %'s of sweet orange oil, bergamot oil, and limonene -- all three can act as degreasing agents as well as add fragrance.
I'm sure the bar smells amazing, but, boy, I think that formulation would be drying and potentially irritating to the scalp. At least it would be for me if I used it on my hair, based on my experience with SLS shampoos in the past.
I would think you could go to the Chemistry Store or other supplier of syndets and buy SLS, melt it with a bit of beeswax for thickening and a nice fragrance, and end up with something similar.
Susan's recipes are more complicated, because she's trying to formulate a shampoo bar that's not irritating or overly drying to the scalp and hair. Although I appreciate that, I also agree with you that it's intimidating. Not so much that it would be hard to make, but that it requires ingredients I don't have already. I figured out what it would cost to buy ingredients for a small batch of syndet shampoo bars a la Susan. The cost turned me off, especially since I have no idea if I'd even like the shampoo bar.