Striker Cameron Jerome will be allowed to leave providing the price is right - with Bolton linked with the former England Under-21 international - and Wolves are also showing an interest in central defender Roger Johnson.
Blues manager Alex McLeish recognises some members of the squad have to be off-loaded for financial reasons after relegation.
But sources close to Blues also stress the need to keep a strong squad to challenge for a quickfire return from the npower Championship.
Players will also not be allowed to leave on the cheap.
Blues want to keep Johnson's defensive partner Scott Dann despite reported interest from Liverpool.
He missed the second half of last season with a hamstring injury and his absence was a key factor in Blues being relegated.
McLeish knows he is at the mercy of Premier League predators and Johnson has also been linked with Blackburn, Bolton and Sunderland. But no formal offer has yet been received for the player and Blues will demand considerably more than the £5million they paid Cardiff two years ago should it prove impossible to keep Johnson.
Loanees Obafemi Martins, David Bentley, Matt Derbyshire and Alexander Hleb plus out of contract Lee Bowyer, Kevin Phillips, Martin Jiranek and Sebastian Larsson have already left Blues.
Source: PA
Source: PA