Booked last night - BUF-LHR - K fare $645 - B fare $789. The $599 B fare starts on 12/24, and we wanted to be there before then.
A V fare is about $500. So for an extra $150 or so, I can use my SWU's. No promises, but track record had been good.
I have no idea where you're getting your $3000+ B fares from.