Is the building owner subject to recourse after evicting me from my business of 15 years resulting in lost business/profits?

This seems like a fairly complicated situation, and one that you should see a lawyer about. First, the tenancy and the eviction. Did you have a written agreement? Commercial tenancies are governed by the CA Civil Code and of course by the terms that you and the landlord agreed on, so whether 30 days is enough notice depends on your agreenment.

"Retaliation" in means that the landlord is punishing you for exercising some lawful right you have. In this case, you're calling retaliation what seems to be the landlord's desire to set his son up in a competing business.

As for taking your clients, I don't see why you have to let this happen. Is there some reason you haven't rented another space and re-opened your business, using the same name and client list? Your clientele probably didn't go to your salon because of its location, they went there because of you and your staff, and you can contact them and see if they'll follow you to a new space.

Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.