"We would all love Darren Purse to stay and we can now make him a better offer as a Premiership club," Sullivan told the Birmingham Evening Mail.
"But we have a team of team-players, no huge superstars, so no-one is irreplaceable.
If Darren wants to go, we'll let him go as long as the price is right for us.
"If we don't get a decent offer then he will stay with us on his current wages for 12 months.
"Who is to say that when he becomes a Bosman our offer won't be the best he gets anyway?"