Thank you for submitting your item for appraisal. This portrait painted after a photograph will probably mean very much to you, there is no measurment for the sentimental value. The art market on the other hand is driven by supply and demand. You and some other people who knew the deceased would be the only ones interested in buying such a painting. Therefore the estimated is based on the sum you had been willing to pay. What a great idea to honor someone who had enriched your life.