The Mirror claims that the Red Devils are expecting to lose out in their pursuit of Borussia Dortmund's Mats Hummels, while possible moves for Arturo Vidal and Angel Di Maria could fall through due to hefty valuations.
However, Van der Sar is sure that the outgoing Dutch coach can work his magic at Old Trafford without requiring high-profile signings.
He told the publication: "Louis van Gaal's best quality is to create a team and to get a squad playing brilliant football.
"Over the last few weeks, the United fans have witnessed how he guided this young, inexperienced Dutch squad to the semi-finals – a squad which nobody gave a chance to finish in the top eight.
"Louis will arrive at Old Trafford with a glowing CV, based on the things he has done in European club football and on this World Cup in Brazil."
Van der Sar played in three Champions League finals for Manchester United, including the victory over Chelsea in Moscow in 2008.