I can't recommend any professional stuff because I'm a cheapskate and don't even bother looking at for-sale sites.
Depending on what you're looking for exactly there are some free items in the free area at
Artist 3D that can be described as Victorian (in the Household section). The problem with that site for
Poser users is that some of that models only come in .max format
as opposed to
Poser-usable .3ds format, but if you have other programs to process .max then it would be no problem for you.