I have been watching this for a while and have noticed that Virgin have reduced the price to fly return to Miami to £308 per adult, from £450 last week. (In my case; 2 adults & 1 infant, total cost is now £690, reduced from £950 last week!). This reduction has happened today. The price seems to be valid on many selected dates between September 2009 and March 2010. Probably similar reductions also to many other USA destinations.