I am new to Maya, but I think you need to decide specifically what you want to learn, whether it is modeling, animating, rendering, etc. $500 won't get you much in the way of specialized Maya courses, unfortunately, based on what I have seen, unless you can find something at a local community college, perhaps. I don't know about the convention scheduling. Your best bet might be to look for online instruction (assuming that's cool with your boss), and practice.