A replica of Shiki's knife is probably available at a sword dealer specializing in anime/video game replicas. They normally have knives and similar blades as well.
I haven't seen Shiki's knife though.
In all likelihood, there are some cosplay shops that custom make stuff. You could probably contact one of those for the knife. His glasses, well, they're not really that special in design. You could probably step into a Lens Crafter or such and find it.