British Airways has a very cheap First Class fare originating in Frankfurt to New York for only about USD 4000.
It is a 6 month maximum stay ticket, and booked in "A" class. I believe the fare basis is: AEE6M and it must be paid for and ticketed in Germany.
"Differential fare construction" is not allowed on this fare, so this means you can't pay a "differential" to upgrade to concorde.