Sometime Today, Rony assembled some asciibets to say:
All those who decide at the last moment and find difficulty in train reservation need not worry. There are daily luxury buses between Mumbai and Bangalore and though its a 24 Hr. journey, at least you have a reserved seat.
There is also spicejet, deccan air, go air and indigo air where even last minute flights are not too expensive. if you're lucky, you might get a cheap jet airways flight in the afternoon (2 or 3pm).