Speaking to talkSPORT, Marsh - who formerly worked for Sky Sports as a pundit - feels Kane is the real deal and will go on to become an even better player than the Premier League’s all-time leading goalscorer Alan Shearer.
Kane has made a huge impact this season, having scored 29 goals in 43 appearances for Tottenham. He will make his first start for England this evening, against Italy in Turin, four days after scoring his first England goal on his senior international debut against Lithuania at Wembley.
"I reckon he is worth £100 million, I honestly do,” Marsh told the Sports Bar. “If I was a chairman of a football club, that is what I would pay for Harry Kane.
"I think he is going to go on and be a bigger and better player than Alan Shearer.”
Marsh: Kane is better than Di Maria
Marsh went on to explain why he believes Kane, 21, must be worth considerably more money than the likes of Di Maria and Eliaquim Mangala, expensive signings who have flattered to deceive in the Premier League this season.
"Manchester City paid £32 million for a relatively untried young player called Eliaquim Mangala. If Mangala is worth £32 million, Harry Kane is worth £100million all day long,” Marsh, 70, added. "Angel Di Maria cost Manchester United £62 million. I think Harry Kane is a much better player than Di Maria, in the Premier League."
Major test for Kane comes next season
While Kane has been a revelation this season, the major test for the young striker will come next term, when he forced to prove that his remarkable goalscoring exploits during the current campaign are not a one-off.
Last season Kane scored four goals in all competitions, but he has been transformed under Mauricio Pochettino into a household name.
Kane is a Spurs fan
Spurs would usually be concerned about the prospect of losing such a talented player - over recent years they have always cashed in on their best footballers, such as Luka Modric, Dimitar Berbatov and Gareth Bale - but the situation is different with Kane, who is a Tottenham fan.
He insisted earlier this year that he would reject Manchester United if the Red Devils came calling, and put pen-to-paper on a five-and-a-half-year contract with the north London outfit at the beginning of February.
Should Tottenham cash-in on Kane?
Tottenham have no interest in selling Kane - and would surely only be tempted if they received a bid involving a fee similar to the price Marsh mentions.
But if Spurs chairman Daniel Levy feels Kane will never score more goals than this season - he could end the campaign with 35 goals or more - then perhaps there’s a small chance Tottenham could sell for a slightly more reasonable price.
The Di Maria comparison, however, is bizarre considering they are totally different players.
Had Marsh compared Kane with Radamel Falcao, however…
How much is Harry Kane worth? Have your say in the comments below!