When to book flights to NY for October?

A friend is getting married in New York in October and three of us are hoping to go over. I have checked a number of websites and the best price that I have so far is €460 return. Should I book this now or are these prices likely to come down closer to the time?
Also if an airline goes bust do I have any way of getting my money back? Would I have more protection if I booked through a travel agent?