I notice there is now "offers" available in the FS section. That is a legal and ethical way for shops to advertise their products.
We might know "$0" means offers but if any retailer quotes that price then they legally have to offer it for.
Heres another fun fact. If a retailer sells a demo product that's out of warranty for below cost to move and it becomes faulty (at your doing but shop cant prove it...) within 3 months, you're still entitled to a refund / replacement