Hoops boss Neil Lennon revealed on Tuesday night that the club had rejected a second bid from Norwich.
Lennon also confirmed Hooper - who has 18 months left on his deal - had turned down a new contract offer but the manager was confident he would still be a Celtic player on February 1.
However, Caldwell - who quit Parkhead for Wigan in January 2010 - believes any club that does succeed with a bid will secure themselves a bargain.
He said: "Having seen the players down in England, I think he would do really well, he would score a lot of goals.
"If you do that in England, there is really no price that you can put on it if you can score enough goals for your team.
"The clubs who are looking at him now would definitely get a bargain.
"I'm sure if he went down there and started scoring goals, he could go to even bigger clubs, like Steven Fletcher did.
"He showed he could score goals at that level and has gone on to bigger clubs since he's been down there."
Reports suggest Tottenham may also be ready to enter the bidding for Hooper's signature.
"I think he's excellent and I hope Wigan are one of the clubs who are in for him!" joked Caldwell.
"I've been really impressed by him. He works the line well, he scores a lot of goals and he works hard for his team.
"He's a real asset to Celtic, as you can see from the amount of money that teams are bidding."
As well as Celtic's resolve being tested, Caldwell believes Hooper will be torn between the prospect of playing in England's top flight and the opportunity to face Juventus in the last 16 of the Champions League.
The defender added: "At the time, I didn't really have the European adventure to stay for. My decision was a bit easier.
"Week in, week out, the Premiership is one of the best leagues in the world and you will get tested at the very highest level.
"It has that draw, that's what I went for, and I haven't been disappointed.
"It's a really tough, challenging league and it's a great league to play in.
"It will be difficult for him because of the Juventus games but, without a doubt, it is a great league."
Meanwhile, Caldwell believes Celtic can create history by booking their place in the quarter-finals of the Champions League for the first time, albeit the fact that they face a tough task.
He said: "It will be even more difficult than beating Barcelona [who lost at Parkhead].
"When you play Barcelona, you know you're playing one of the greatest teams in the world.
"People ran an extra 10 per cent, people worked an extra 10 per cent harder because it was Barcelona.
"Juventus are a great side in their own right but they don't have the aura that Barcelona bring.
"Over two legs it will be a more difficult tie but, without a doubt, if they perform as well as they did, I think they can beat them."