Originally Posted by
RockyRobin
One could also calculate the cost of the avios on how they were sourced. For the ones I get through general spend on my credit card for example I cost them out as free as apposed to say the Balance Boost I did last month
They're not really free though, given the opportunity cost - you could transfer points to an alternative airline/hotel scheme or even get cash in many cases. There's also the opportunity cost to spending the Avios.
So I always calculate the best value redemption option based on a nominal value of 1p/Avios.