Originally Posted by flarmip

The 40% bonus sale is fundamentally still poor value - you are still paying far too much per Avios (far north of 1p each) for it to be worthwhile. Avios Booster is far better value, you pay only 0.92p per Avios if you choose the 3x boost option.

Using Avios to reduce the cost of a cash booking is also rarely worth it. The only time when it's worthwhile is for the lowest reduction, e.g. 10k Avios for £100 off as you then get 1p per Avios.

The best value would be an F redemption but as you are a Blue member I suspect you will not have a Gold Upgrade Voucher or Joker available to force open availability...