Hello Rachel you can find lot of leather, nylon synthetic bands from online stores but it might require additional stitching. I have used such type of things and I have also tried with Velcro Bands tied around the wrist. They are completely sticky and gave out excellent results without error because of it. 

Otherwise go for ordering from the link below they are manufacturers for such kind. And lot of suppliers can be found from china and Link is as follows.

http://www.rfidwristbandworld.com/rfid-nylon-wristband.html

http://wtoprint.com/

Thanks very much Frederick. Much appreciated. I will have a look...

We use different accelerometers, but they do have soft velcro armbands that are detachable. You can buy them seperately.

http://sensewear.bodymedia.com/

Good luck

Try these guys - https://www.cousinsuk.com/

Thanks for your input everyone. We've found a local manufacturer who is going to fabricate some for us. Happy to pass on the details.