I know your pain. I have gone through half a dozen shoulder rests and four chins rests trying to find the ideal set up. The combination of shoulder rest and/or chinrest is very personal so Amazon is a good place to try out equipment, as CorinnRadd suggested, because you can return stuff with ease. I have found that the Bonmusica shoulder rest works well for me. It was a bit pricey but it can be adjusted every way imaginable.
