Best prices I can find are ex-MIL and returning into AMS.
You can gain 440 TPs for £1,038:
LIN-LHR-BOS-LGA-BOS-LHR-AMS
You can also route something like this for 520 TPs and £1,192, including AY A350 on the HEL-LHR-HEL legs if you wish:
AMS-HEL-LHR-JFK-LHR-HEL-FCO