I thought Digital village as local stockists would have it but they dont seem to
Im imagining that any sound samples FX will work with Sony Vegas as it is a very audio oriented software having its roots in Sound forge .
That said, the Boxed version of the Movie Studio version comes with a CD with Sound FX samplers from the extensive linked library
I just think the Sony samples are costly and if any other will work with Vegas you may try it by just doing a simple search for royalty free music samples sound FX
Some magazines even give then away on cover mounted discs as a taster