Taxi cost from Milano Centrale to Linate airport

A taxi from Milano Centrale station to Linante should cost €25-30, unless it's late at night or early in the morning, when they cost more. There's also a shuttle bus which costs €5, 2 per hour, takes 20 min. www.airportbusexpress.it.

There is not flat taxi fare to Linate, it's based on the meter, so it will depend also on traffic, but I'm more inclined to say that it will likely be a bit more than €30, probably closer to €35.
The bus is another option, as mentioned above.
If anybody asks you for 60€ to 80€, avoid them. Those are dishonest crooks.

I went from a hotel by the duomo to Linate and it was $20 if that helps at all