If a guest does a non-dated search on Airbnb, you can specify the base price that you would like to display.
To set this price up go to Properties > Edit > Web details >> Airbnb data (to the right of the property) > Go > select the Rates tab.

As the light grey text states, if you leave it on the default 0, the guest will be quoted the lowest price for one night that has been set up for the property..