Plumping Wash Densifying Shampoo

I hate the fact that this shampoo is so good because it is outrageously expensive. I have fine hair that is transitioning to grey (ugh) and this is the only shampoo (along with the conditioner)...

Relatively inoffensive shampoo, does seem to help reduce fall as it claims, but after 1 month of using every second day my scalp has become extremely greasy. Unfortunately the accompanying...