It's open to negotiation. However, two points are worth bearing in mind. On the one hand, the price may be much lower than the average house asking price -- which will limit an agent's interest in spending money on promoting it. On the other hand, it usually takes much longer to sell raw land than houses -- which can further reduce an agent's incentive to advertise the property.
The main exception is with land that can be developed, which is likely to mean a price in the hundreds of thousands (or even millions). While this limits the number of potential buyers, it can also attract an agent with all the "right connections."