You don't get it do you? Higuain, was proven, experienced, had just had his best season, was purchased from a hated rival, had a number of years on his contract still, inflation, yet couldn't even fetch 80m. Inspite of all those hurdles. I don't care about Kane's age. Given the above there is no way he goes for 20-30m more than that. Because like Higuain, he simply isn't worth that fee.
Which is all irrelevant to what he is worth. £100m for a Kane is a rip off for the purchasing club, period. For Spurs, they have every right to ask for whatever they want. He is happy, on a long term deal and they have zero need nor reason to sell. In Spurs shoes, you'd be mad to start any negotiation below 100m. For that reason alone the deal isn't worth it unless the buying club are just plain desperate.