Appraisal values
 

I am trying to find information relating to the sale price of aircraft (typically single aisle - 737, 737NG and A320) against recent appraisal value.

As I understand, it is quite common for a single aircraft to be sold at below appraised value, but a portfolio of aircraft tend to be sold at appraised value.

I know it's a broad question, but do the above comments hold any truth?