The Sweden striker is expected to be out for around six months after rupturing his hamstring, while the former Netherlands captain is suffering with a knee injury.
Coach Dick Advocaat had called on the club to bring in reinforcement in the winter transfer window, but Brands has said the club must balance the books and new signings look unlikely in January.
“If we do that [bring signings in], then it is only if it is a responsible investment for the future,” the 50-year-old told Eindhovens Dagblad.
Instead, Brands is looking to Feyernoord’s policy of bringing forward players from the youth team as a way of saving the club money.
“First, we'll look at when Erik Pieters returns from his injury and how the early stages of Toivonen's rehabilitation expires.
"We've seen how a young talent can suddenly show up at Feyenoord."
PSV are currently second in Eridivise, one point behind leaders Twente on 24 points from 10 games.