How do you consider individual league and then also club influence on value?
Valuation is calculated based on Rating, Age and Club.
The Club Bonus is determined from the Club Rating. Lower the Club Rating the lower the bonus.
If the player is less than 80 rating he gets no club bonus (deemed a youth player). If however he's over 80 rating the player is awarded a fraction of the Club Bonus, higher the rating, higher the Bonus.
Club...................................Club Rating...............Club Bonus
Real Madrid...........................1227.0..................£11,570,000
FC Barcelona.........................1201.9..................£11,319,000
Bayern Munich.......................1071.8..................£10,018,000
Juventus FC...........................1026.5..................£9,565,000
Atlético Madrid.......................1009.6..................£9,396,000
Paris Saint-Germain................916.3...................£8,463,000
Manchester City......................901.4...................£8,314,000
Sevilla FC..............................798.6...................£7,286,000
AS Monaco............................749.5...................£6,795,000
FC Porto...............................731.3...................£6,613,000
SSC Napoli............................721.4...................£6,514,000
Arsenal FC............................718.7...................£6,487,000
Manchester United.................711.9...................£6,419,000
Now as it's based on Club Rating, the Bonus will improve if the Clubs form improves. This means the valuation system is fluid and will match how a Club is performing. A player might have the same rating but if the Club Rating drastically improves his valuation will improve. To get the full bonus you need to be 99 rated, currently nobody in the database is 99.