It's the same polysorbate 80. Polysorbate 80 is cheap... $5 a bottle is normal.
It isn't a shampoo by itself, though. That's why I use the shampoo version. It has the hair cleaners mixed in.
I don't know if straight polysorbate 80 would clean your hair the same or not.
Guys who use straight polysorbate 80 put it on... wait... then rinse it out and use a regular shampoo.
Since the polsorbate 80 shampoo Inner Shampoo only costs 6 bucks... I use that and save a step.