My husband is a Dutch Ostendorf. We are told the village is in the Black Forest, southern end. We tried to find it once, but traffic was SO bad along the way, we finally had to give up!The story we have, is that they founded the village, but they were a motley lot - thieves, rapists, ect..My husband's line left for Amsterdam sometime in the 17th century, I believe.
There are a load of Dutch Ostendorfs in Holland, of which my in-laws can connect you with- but they may want to get permission first. In America, there is my husband's parents in Arizona (immigrated to the USA in the late 1960's from Amsterdam via Rhodesia) and his brother's family in California.