Now that the transfer window open again I just wonder what was your best investment for a transfer till now.

For me it is this player:

http://rockingsoccer.com/en/soccer/info/player-30342

His estimated market value right now is 5 times more then what I paid for him!

My best is probably the player below, I bought him in the first mid-season trade period for $29000 & sold him last mid-season trade period for $208,642 an increase of 719%.

http://rockingsoccer.com/en/soccer/info/player-20393

The only other noteable tradie was for the following player, who I bought for $65,000 & currently has a market value of $408,000 an increase of 627%.

http://rockingsoccer.com/en/soccer/info/player-20249

Hubert Arnaud (http://rockingsoccer.com/en/soccer/info/player-19702) has increased by about 580% to $548,000, and should continue to significantly improve over the next few seasons.

These two players have improved by about 430%:
Phil Hume
http://rockingsoccer.com/en/soccer/info/player-34699
Oscar Denavarro:
http://rockingsoccer.com/en/soccer/info/player-7104

I would be interested if someone could determine at what age the marginal growth of market value is surpassed by the marginal growth of wages for the average player. This would help to determine what age to sell an investment player or players from the youth center that will clearly never make the starting squad. Maybe I'll try to motivate myself to keep some statistics for the purpose. It would probably be enough to keep track of market value, wages, and age (perhaps as of the start of every transfer window). There would need to be assumptions about the training center, health center, and expected number of matches.

Although the proliferation of the knowledge could decrease the value of players (if they are sold after they are known to be unlikely to produce a future profit), the rather fixed market prices and the probably relatively inelastic demand should minimize that problem.