I've been offered £149 for LHR - GIB, 2 days before the flight (didn't take it yet).
Edit: they claim it's a "special limited offer"... I assume it won't drop below this amount then.
For the record, the same upgrade if using avios is £13 + 7500 points.
Last edited by LXGB; Apr 12, 2018 at 4:46 pm
Reason: extra info