There are many people who had started farms recently in Trichur, Pathanamthitta, Idukki, Wayanad etc. Barring land, you can take it as 1 Lac per cow, which includes cost of the cow, housing, milking machinery, fodder harvesters, fodder chopping machines, feeding utensils, calf bottles etc.
Land cost not included. Start only if you are able to supervise. Otherwise your money will be enjoyed by others. Or you need a very sincere guy to man the show on whom you can rely completely. What the cow has eaten, whether it has got stomach full, how much milk did the cow gave that day, veterinary expenses, see all these you need to believe what that guy says. So getting such a guy is one aspect, if not your presence is very much needed during milking and feeding time. Definitely its a good business, as anything that is coming out of a cow is money. How you make money depends on how you apply its usage. Urine, dung, milk are all money. Who will buy, how can you sell it, how to collect it, should be studied. Try to sell the produce to the end consumers to make maximum returns.