You would have thought this is an easy task but there appears to be close to no one who sells desk chairs that are purple. Doesn't have to be the whole thing. Only require is that it be an adult chair.
The only one I've found is http://www.mattblatt.com.au/Task-Computer-Chairs/Ergonomic-T…
and this http://www.convenientinteriors.com.au/m_wholesale_furniture/…
Need to be here before Christmas.