Bacopa monnieri is a plant of immense medicinal value. It is generally used as brain tonic. In Mumbai this plant may be available in herbal garden. The following links may be helpful to you in getting this valuable plant species. 

http://www.indiamart.com/proddetail/bacopa-monnieri-brahmi-5356614548.html

http://dir.indiamart.com/impcat/bacopa-monnieri-extract.html

Any ayurvedic store. Even amazon has it

Brahmi (Bacopa monnieri)  is a plant extensively sold in India and in many parts of the world. I am pretty sure you can find a good supplier, but you have to find a good identity test method and traceability paperwork to support your study.  Be aware that many suppliers can substitute or dilute your plant. For example,  Centella asiatica, Eclipta alba and Malva rotundifolia are common adulterants sold in the name of Brahmi. Eclipta alba and Malva rotundifolia are economic adulterants added to increase its concentration. Since, these herbs are marketed as dried leaves, or extracts, it may be difficult for you to ensure authenticity using taxonomy. Your colleagues: Aradhana Yadav, et al from the Molecular Ecology Laboratory, Department of Botany, Faculty of Science, at Hamdard University, New Delhi, India, came up with a DNA method to deal with this problem. Here is the link to their paper:

http://sciencedomain.org/abstract/453

You may want to collaborate with them. Thanks.

Contact Chetan Shah

022-66541696