Regardless of the price, most bath soaps in the soap aisle have the same basic ingredients used in soap making. What differs is the additional ingredients like moisturizers and fragrance. Of course there are more natural versions out there. It's a good idea to read the ingredients list before purchasing.
And if I'm planning to try a different product, I try to read customer reviews online. For example, I was going to purchase a new box of bath soap last week but backed out when one review said that the soap leaves residue on skin. So customer reviews can be very helpful.