At the moment there are almost no transfers for top players.  Look at the auction and lots of players but they alll have 0 offers. I think it should be possible for managers to make an offer for any player from another club and the other club can accept of decline. I don't think auctions are working for the 3, 4 or 5 star players at the moment.

already propose..but for sure fake selling will happened :/

to help manager to have the right price maybe Nicmo can add a selling history (AVQ, Potentiel and price)

There should be a maximum price - so that a 1 star, 45AQ player couldn't be sold for 10 euro. But yes, agreed it could may be an issue.

Maximum price wouldn't solve the issue, you could still sell a strong player for a few cents. Direct offers can only work if, after the owner accepts, the player is automatically put on auction with the accepted offer as the starting price