I've had several mothers asking me where i bought my materials. I thought i should also write it here for the benefit of others.
This was passed down to me by my sister. She bought it from Shichida school. I guess it would be easy to purchase if your kiddo is already a student there...but i am not sure if its sold to the public neither do i know if this product is still available.
Montessori Maths Beads
I bought the a set of Montessori materials which includes materials from sensorial to mathematics which of course includes the beads. I ordered through a bulk purchase from Singapore Motherhood Forum and unfortunately, i've not seen anyone organising this spree anymore. However, i do know of an local online store that sells the same product and a whole lot of Montessori materials. But please note, i've not bought from here before so i am not certain about its credibility or reliability. If you are not comfortable, please do not to order.
Here's the website (just click on your interested category on the left panel i.e. Mathematics):
Hope this helps!
(Schida and Right to learn Educational Service should reward me for this! :P)