You missed the point. Have you even played it? If you ask for a lot more money than a club bids for your player, they will ALWAYS cancel the deal. So if someone bids £12m for your 100 rated player and you ask for anything more an a few million over that amount, they'll cancel the deal and your player ALWAYS hands in a transfer request, even if the club bidding is miles worse than your own.
My point is that the game rates Messi at, say, £30m, so if you bid for him it'll take about £70m+ to sign him. That's fine. No problems with that.
But if my team has a player rated the same as him, say at 100, the game doesn't let you set how much he's worth. So the game makes him worth £9m compared to Messi at £30m.
Whereas to sign a £30m player you'd need to fork out £70m or more, if a club bids for your player at £9m they NEVER go any more than a few million over his 'value'. If you respond and ask for more money, the club will ALWAYS reject the deal and pull out.
The result is that to BUY a player rated at 100, it costs between £50-80m, but you can NEVER SELL your own 100 rated player for the same amount. The most other clubs will bid is around £12m, and all because the game doesn't let you set your own valuation.