I have a complete SEQ4 knob set for sale. 21EUR for the knobs with one data wheel of your choice. For 24EUR you'll get both data wheels. Please add 5,60EUR for international insured shipping.
Dimensions of the knobs:
http://www.albs.de/ecom/images/866003.pdf
http://www.albs.de/ecom/images/860018.pdf
Best regards
Martin