Samvat Rice / Buckwheat Flour

Hi friends,
Where can I get Buckwheat flour in Bangalore?
And where can I get samvat rice (rice that can be eaten during fast or vrat)?
I tried many malls and rice traders, but could not get so far.

Can anyone help me out?
Observing 10 days Navartri vrat, so need these.

Thanks in advance.