Gold prices vary on a daily basis. The best thing for you to do is visit some gold sellers which are managed by Indians and they should be able to update you on the latest laws of India on gold imports. Take this step say a week before you plan to leave Doha. You can buy gold in any form from any of the jewelers in Doha. You don't need to take any precautions as such. Make sure that you obtain a receipt for the purchase you make and have your name on the receipt.