What are the benefits of participating in workshops related to good conferences?
At a certain point in your career it might be very valuable to attend. In some CS fields workshops are a great place to extend your learning. They are also a great place to make professional contacts that will serve you well as you grow into the profession. I don't work in Machine Learning, however, and can't speak specifically for workshops at this conference. 

In some conference, "workshop" actually means getting help in improving your work or at least getting feedback on it from a wider audience than you normally have. This, again, is valuable for a new scholar. 

If you haven't attended a lot of good conferences, attendance itself for a student can be very valuable for the same reasons stated above. Senior faculty will often wander around in the poster area just to meet people, encourage them and look for potential future junior faculty. 

Like anything, you may need to balance the funds against other opportunities, but it could, depending on circumstances, be well spent here. If you haven't been to the conference in the past, your advisor or other faculty can give you an idea about what goes on.