It would be lovely to be able to estimate transfer value of players, own or transferlisted.
That would give us some orientation about what to expect from sale, or how much to bid without getting into excess for less valued player.
I do not expect from game to calculate estimations. This could be achieved by listing similar players that were sold recently together with prices they went for.
If privacy of those players is an issue, they could be listed anonimously, with only their stats shown. Age and nationality included, of course.
It should nor be hard to find players with high similarity. Differences in each skill or age could be translated into a weight and the game would then show e.g. 10 players with the smallest weight.
Also would be good to check transfer price estimation for an kmaginary player - e.g. how much could I expect for my player if he gains 2 more balls by training for next season?