The Blues signed Germany international Havertz from Bayer Leverkusen last week in a deal costing more than £70million.
Havertz, 21, penned a five-year deal with the Premier League club and has become Chelsea’s second most expensive signing following goalkeeper Kepa Arrizabalaga.
Berbatov is a big admirer of Havertz and believes he will thrive at Stamford Bridge but still says Chelsea paid too much for the German.
The former Manchester United and Tottenham striker told Betfair: ‘I think the amount of money Chelsea spent on Kai Havertz was a little too much for my taste. It’s ridiculous, it’s too much money.
‘Havertz is a great talent, and I have said that in the past, I am a big fan of his and with my Leverkusen connection I was keeping a keen eye on him every week, but still the money that they have paid is crazy.’
Despite questioning the fee Chelsea paid for Havertz, Berbatov has heaped praise on the attacking midfielder and backed him to flourish under Frank Lampard.
The Blues finished fourth in the Premier League last season but have been tipped to challenge for the title this term following their summer spending spree.
Berbatov added: ‘He’s a great signing for the team, along with Timo Werner, and they certainly have the talent to challenge for the title next season, but the test is going to be a big one for them.
‘His vision of the game, his positioning, that pass in the final third he can deliver, his finishing and his intelligence are all things that we will see from him in a Chelsea shirt.
‘From what I was hearing at Leverkusen, he really wanted to make that next step in his career and that shows confidence, he’s telling people he wants to move forward at that early age, and especially with moving to England, one of the best leagues in the world with the best players.’
‘It will also be a big help that he has Werner in the dressing room with him,’ Berbatov said.
‘When you go to a new place and you have a team mate who is the same nationality, or someone that has played in the same league as you previously, it is massive help
‘It feels easier to fit in and he won’t be the only new boy there.’