Bent took his tally for the season to 21, 20 of them in the Barclays Premier League, with a quickfire double in the Black Cats' 3-1 home victory over Birmingham.
The former Tottenham man, whose total fee is dependent on appearances and goals, eloquently stated his case once again for inclusion in England boss Fabio Capello's World Cup squad.
Bruce said: "He has done fantastically for Sunderland and he is worth every penny. It just shows you that a bit of quality, playing every week, he has flourished with the chance we have given him. He has been terrific.
"Where would we be without him. But that's the difference.
"You pay £10million, £12million - he will probably end up costing us £14million or whatever it is, but that's the difference.
"It's the next step."
Bruce was once again diplomatic when asked about Bent's chances of forcing his way into Capello's plans.
He said: "He must have an outstanding chance because the one thing he has got is he is a natural goalscorer. We have got very good strikers, but he gets into the box and he gets it on to his left foot, you know, you say 'goal'.
"That's what he has done for us repeatedly, so he must have a chance.
"Whether he will go, who knows?
"I haven't spoken to him, but come on, it's a World Cup - playing for England in a World Cup? He's got to be [desperate to go], I would have thought. But I haven't had a conversation with him."