last I heard there were only 6 known sarloos wolfhounds in the united states, all imported and there hasnt yet been enough interest in the breed for anyone to try to qaulify as a breeder, therefore those imported dogs are all neutered/spayed. the breed was developed by Leendert Sarloos in the early-mid 1900's, he died in 1969. he crossed canadian and siberian wolves with german shepherds. the sole purpose of the crossing was to try to eliminate hip displasia. the problem was that wolves can also develop hip displasia, and they didnt understand genetics at the time and some of the german shepherds used in the breedings either had hip displasia or produced it in their offspring. also he was not breeding for temperment or working ability, only crossing wolves with german shepherds. it IS a recognized breed, by the dutch kennel club, due to the fact that he used many wolves and many gsd's, and didnt continue cross breeding the offspring of every generation back to purebreds of either breed.
they do not differ from any other wolf dog though, in any way. they are very shy, very independent, very aloof, and have a very strong pack instinct. due to their nature of not being a very tractable/trainable dog wich are very prone to becoming fear biters, they have not become popular even in the netherlands. what little I know about them is from reading and from talking about them with a friend of mine who lives in Belgium and breeds german shepherds.
and as far as looks, the majority of them look more like german shepherds than they do like wolves. the only physical trait they inherited from wolves (due to the fact that for every wolf used in the program, there were 4 german shepherds, so basically after so many generations all sarloos wolfhounds are 95% german shepherd and 5% wolf) is there coat color. this color is gray sable, which is also found in the german shepherd. sables are almost non-existent in american lines gsd's, but quite common in german and czech bloodlines. the sarloos is built like a gsd, same hight, same weight, same proportions. my friends best guess was that for importing a sarloos from a dutch breeder you would pay in the neighbourhood of $6,000-$10,000. you can easily import a awesome german shepherd for that price, and have a dog that is highly trainable, not afraid or shy, and that has health, hip, and temperment garauntees. I imported my current german shepherd male from my friends kennel in belgium. he is from top showlines, schutzhund trained, and an amazing fmaily/house dog and I paid under $5,000 for him plus shipping fees.