Wirelessly posted (BlackBerry8530/5.0.0.601 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)

Both Aer Lingus and Icelandair offer reasonably priced one-way fares from London to the U.S., but a connection en route would be required.

Depending on when the OP plans to travel and how much luggage is being carried, a fall repositioning cruise might also be a cost-effective alternative.