For those who are interested in the genuine sunblinds for the A2 :)
I have bought the complete set of sun blinds in a german bosch service garage on ebay for 44 €.
http://cgi.ebay.de/Sonnenrollo-Sonnenschuzt-Rollo-Audi-A2-Heckscheibe-/260631694097?pt=Autoteile_Zubeh%C3%B6r
Back door...