If you can make it to Inverness from home, the return price on BA to JFK (INV-xLHR-JFK) is £6100 using AA codes (BA metal) or £6126 using BA codes.
If you can manage the time or suffer a short non-Oneworld positioning flight, return from Amsterdam to PHL (BA via LHR) is £2977 (AA codes) or £3003 (BA.)