Filching bobbin cases?! Yikes. I never would have thought.
The prices are coming down even in just the couple months I've been looking. With patience and diligence you can definitely find them under $200, even under $100. I think the ones that go for $300+ right now is because they are a special one in some way or someone wants the "buy it now" option for instant gratification. Depends on what your times worth.