I shall also put it in the context of a pure status chaser needing 320 Tier points to get over the line for Gold renewal with a 50k+ Avios surplus.
If they find 2 nested back to back CE returns to Sofia in the region of £200 each which is possible ATM they can effectively do it for a net 36860 Avios. { The Sainsburys spend of circa £346 / 43,250 Avios + 6000 PP Avios - 12660 earned. }
The cost of this is just over 115 Avios a tier point.