Bellingham's value has gone up by a few million pounds after making a positive contribution towards England's Qatar 2022 World Cup campaign which ended at the quarterfinal stage with a 2-1 defeat to France.
Liverpool are one of a number of clubs linked with a big money move for the 19-year-old, with Real Madrid and Paris Saint Germain also in with a shout.
Former Liverpool midfielder Hamann acknowledges Bellingham's undoubted talent but believes his old side will be overpaying for his services.
"I'd be careful with Bellingham right now. He's an exceptional talent, he showed that at the World Cup, but if Dortmund ask for £100-million odd, £140-150 million, it's a big risk as well," he told Talksport.
"I think with Bellingham he's got to find a position. He models himself of Steven Gerrard but I don't think he's got the ability and pace going forward like Gerrard had.
"I think you need to wait and see where he finds his spot in the midfield two or midfield three in the future, and to pay £150million for an 18 or 19-year-old, I think it's a big risk."
Liverpool have already made a move in the January transfer window after agreeing a deal with PSV Eindhoven for the transfer of Cody Gakpo.
Hamann has given a thumps up to the move for one of the World Cup's breakout stars.
"They have needed a player like him for the last few years. I don't think they have enough of a goal threat from midfield," Hamann added of Gakpo.
"They are always a threat from set-pieces and that will be strengthened with his size and physicality. And in midfield, at times I feel they lack a bit of physicality.
"They don't have a player who has the physicality that he has got. I always look at Joelinton as a player in the mould Liverpool needed because he can drive from midfield, he can head the ball, very good technically, and he has got a bit of pace about him as well.
"He is a great addition and I hope we see a lot of him in the next few weeks and months."
