@Ooviya You can get it on all Naatumarundhu kadai or palm sugar is available at saravana provisional store, T.Nagar, Chennai
Get it from stores like dhanyam or team shoppe if it is for kids. I find the one in dabba chetty shops having some sand. Or ensure you filter the drink.
Did you try Khadi stores? I got it from Mount Road Khadi once. Slightly overpriced, but good quality. -rgs
I also buy the big size pieces of palm sugar or black salt and powder it myself in mixie. @rgsrinivasan yes mount road khadi is good,.