Hello Paul,
It depends on what you want to do with it.
Error reading and coding only:
http://shop.dieselschrauber.de/product_info.php/products_id/36
respectively / or rather / that is to say
http://shop.dieselschrauber.de/product_info.php/products_id/221
The current VAG-COM (now called VCDS-Plus), including the license and free software updates, is available in the following versions:
http://shop.dieselschrauber.de/product_info.php/products_id/45
respectively / or rather / that is to say
http://shop.dieselschrauber.de/product_info.php/products_id/46
http://shop.dieselschrauber.de/product_info.php/products_id/329
Disadvantage: more expensive. Advantages: it offers comprehensive functionality, including service reset, etc., it has the latest VAG-COM or VCDS version in German, and it includes additional software (KDataScope, KPower, etc.).
Best regards, Rainer.