Yes, anyone can go to the WAI conference. I attended the 2013 conference and believe that it helped get my resume reviewed which led to getting the call (email) for the interview with Delta. It was an expensive weekend, but in the current environment you gotta do everything in your power to set yourself apart.

When you do attend any of these conferences, dress the part, shine your shoes and network, network, network. After the conference/career fair ends, the hotel bar is also a great place to 'send the vibe out'; you never know who you may end up having a conversation with.