If they want to sell the player they'll let him go for the initial bid price on most occassions - however if they don't now there are two interested teams they'll sometimes reject both hoping for a bidding war to start ..
Noted and thanks for the response Marc. However, I did consider this so I started to wait until the bid had been accepted. I would then bid and the bid would be accepted (as in Duff's case recently) and then the transfer would be cancelled because he would agree a deal with the other club before I had the chance to offer the contract. Surely IRL his agent would say hang on a minute the European champions are interested?