I thought perhaps a customer buys one just to see the quality.
I believe other sites may offer samples. Who is going to buy a lot of wedding items without seeing it (regardless of the return policy)? I've had a few invitation sales but they are small. A few recent "wedding planners" so I'm hoping they come back for the same design invitations etc.
The one thing about paper products as opposed to other products, they don't seem to "discontinue" or "out of stock".