Keep trying!!!! I've recentley booked a flight with the above mentioned Opodo for 7 of us to travel to NYC in August for �198 each flying with Virgin Atlantic. These flights are few and far between during the high season and it took weeks of being on the net for hours at a time to find this flight. What you should also tke note of is that Opodo often changes the prices at any given time, I know this because when I tried to book another seat at the same price some hours later the price went from �198 to �567. You could also try booking a flight in the low season, you are more likely to find those magic �200 fares although they may be non direct flights with airlines like Air France, Air India, American Airlines and Air Kuwait.
Good luck!