Trip from banglore -> mysore -> coorg -> maglore

Hey Mysore,

I am from Mumbai and I am coming with my family to banglore.. we are planning to go Mysore first.. stay there for 2 days and then from Mysore to coorg.. and stay there for 2 days then the return train is from Mangalore.. I know it's a very dumb move but I fucked up while booking the flight.. So can please anyone help with the suggestion.. i talked to one cab driver.. he's giving me a whole 5 days trip for 20k including all fuel charges and toll, but some of my friends are saying that it's very expensive and it's better to travel by local buses. Please anyone tell me what is the best thing to do here? I'm really confused.