create a sales item for window cleaning as a secondary occupation

I’ve just started working as a window cleaner as a secondary occupation. I always set a flat rate.

So the price is determined after I’ve visited the property.

e.g. window cleaning, ground-floor flat, single glazing and exterior

e.g. window cleaning, terraced house, ground floor + first floor, interior and exterior including window frames ………..

How do I enter a price in Dexxter? Because the price is different for every property. Can this be updated later?