I recently bought a Leuchtturm1917 Bullet Journal from Spot The Craft, a seller on eBay:
for $12.99 + $4.99 shipping from Canada to the US.
The lowest price I found anywhere by $7.
However, the seller sent me a regular Leuchtturm1917 by mistake. When I contacted the seller to return the notebook for replacement, they told me to keep it, as an apology, and sent me the Bullet Journal I had ordered.
When I received the correct journal, I found that the seller had included a set of Copic Multiliners as a gift, along with a hand-written note.
Probably the best interaction I had with a seller on eBay ever.