The former Villa manager, who brought Benteke to the club in 2012, believes the striker could complete a big-money move in the coming months.
Benteke has been linked with Liverpool and boss Tim Sherwood, who replaced Lambert in February, has confirmed he has a "substantial" release fee clause in his contract.
Lambert brought Benteke to England for around £7million from Genk and he has scored 49 goals in 101 games since.
And the Scot believes Saturday's 4-0 FA Cup final defeat to Arsenal could have been the 24-year-old's final game for Villa.
Lambert, speaking at the Tesco Bank Football Challenge at Hampden Park, said: "It looks like if he is going to go, it will be this year.
"But I had it every year I was there that he probably wanted to go, because he was playing that well, you can't stop teams coming in with that level of money.
"It depends how Aston Villa want to view it now
If Christian goes maybe they will get money to buy someone
But as a goalscorer and a player, he's top class.
"I saw it a few years ago
In his first year at Villa he was only behind Cristiano Ronaldo and (Lionel) Messi in terms of goalscoring ratio, which was an incredible achievement.
"He's certainly good enough
He's only 24, he's got years ahead of him
Okay he didn't have a good game on Saturday but he is a top, top player."
The Belgium international is expected to command a fee of around £30million but Lambert believes he will be value for money.
He said: "What is anybody worth now? You don't know
Transfer fees are ridiculous for players you would never think would move for that amount of money.
"But if you go by what Benteke brings in terms of his goalscoring ratio, he's certainly up there if you are going by modern day values."
Meanwhile, fellow forward Andi Weimann is assessing his options at Villa after being left out of their FA Cup final squad.
The striker could leave the club in the summer under Tim Sherwood's rebuild, Press Association Sport understands.
His FA Cup final snub is just one of the reasons why Weimann is considering a move after struggling for game time under boss Sherwood.
Weimann was an unused substitute in their final six Barclays Premier League games before being left out of the cup final squad as Villa lost 4-0 to Arsenal on Saturday.
Staying at Villa Park remains and option for the Austria international but he is aware his days could be numbered after falling out of favour, starting just once in Sherwood's four-month reign.
He scored four goals in 35 games this season but failed to find the net in the Premier League after November.
Sherwood has confirmed he has told some players they can leave with the futures of Aly Cissokho, Carles Gil and Philippe Senderos also in doubt.
Source : PA
Source: PA