Technically a property can be listed at any price, however deliberately misleading a client as to the market value of the property to guarantee a listing is an ethical violation. This practice is commonly referred to as

"Buying" a listing

Explanation:

In real estate, the term "buying a listing" is generally used when an agent or person confidently tells you that a property you own can be sold for an outrageous amount (usually above what its worth), in order to get your listing.