I have used these too. However, I am not a big fan of them. I would use a soap to make a shampoo though. I rather buy large bottles of ready made ones which suit my scalp and use them for long time.
@Decenlady with the advent of TV and other sharp ways of print and other media publicity by shampoo manufacturers the homemade items are losing their importance even if they are not as useful or cost much too higher than what one can derive from home made products. And, shampoo is not the only item in that category.