I talked to a Sonax employee at SEMA last week and he told me that they only offer approximately 20% of their products in the USA. He gave me their US contact info: Vision Investments LLC, (317) 295-7056, www.sonaxusa.com
He said that I should be able to find their entire line of US products from them. Although I don't know if this is entirely true considering they only list 15 products on their website and the Sonax rep told me their full line (in Germany) consists of over 120 products. So 20% of ~120 doesn't really add up to only 15.
You might give them a call and see if they carry any more Sonax products than those listed on their website.
I hope this helps.