should be easy but its proving to be a mission impossible. Im looking for a few meters of elastic, the type you see in shorts or headbands etc, any idea where to find it? I tried MBK but honestly I wouldn't even know what section to look and trying to explain it to bored shop assistant is just to hard

Have you tried a local market or mall fabric selling store?  It is easily available and believe that is where it is sold; along with other sewing items.  Should be easy enough to describe even if you have to show stretching of waistband. 

Good ideas, I know a fabric store around the corner.

cheers

I was in the same situation. I looked for rubber bands everywhere until i found some at siam paragon near paper department.

I know where u can buy it. Bts udomsuk. Side opposite "Honda". It'll be market like bazaar. Go straight, it'll be shop with button, some things for girls and it have "elastic". I Bought it for my child. We created with "elastic" some fich