On arriving at Ahmedabad airport there is a duty free shop where you can get a tourist permit as so long as you buy drinks from them (they only sell spirits and wines). The permit is free. They will stamp your visa and photocopy your passport and ask for your name and both your domicile address and the address where you will be staying in Gujarat.
If you are a beer drinker get your permit from a wine shop as if you buy a spirit from the airport just to get the permit you will have to wait 10 days before you are allowed to buy alcohol again.
The permit is only valid for 30 days and you can only buy drinks every 10 days so make sure you buy your full allowance or you may run short.
Also remember to take your passport with your permit when you do go to buy more drinks.
You are allowed 1500ml of spirits or 20 bottles or 26 cans of beer. (You can mix e.g. 1 bottle 750ml spirit and 13 cans of beer)
YOU MUST get your permit within 7 days of entering the country. (i'm not sure what happens if you enter in Mumbai or Delhi stay there for a week and then go to the state of Gujarat, i did ask the local wine shop person and he said a permit would be granted BUT i can not guarantee this is true)
A list of wine shops in Gujarat. It's part of the permit but if you're not getting your permit from the airport it may be of use.
