The Red Devils have been linked with a big-money move for the Wales international after Spurs failed to secure fourth place and a spot in next season’s Champions League.
“It’s not about the money, it’s about getting the best players to your club and the message that sends out,” Thomas told the Manchester Evening News.
“If you can entice the best players it tells your rivals that you are going for the title again.
“That’s what the message has to be: ‘We’ve won it and now we are going to sign players from the top drawer to make sure we win it again’.”
He added: “Players like Bale and Ronaldo send shudders down the spines of your rivals.
“Bale is already a world-class player and he is only going to get better.
“He has added so much to his game and can attack from anywhere. He’s a goal-scorer, a provider and has so much power. That’s what defenders hate.
“When United have had their best success it has been because of pace. Bale would add to that. He can score free-kicks, headers and tap-ins. He was the outstanding player in the Premier League last year.”
Spurs talisman Bale scored 21 Premier League goals last season, earning the PFA player and young player of the year award in April.