They will pay happily £1 for the door.
Had a customer ask me to do it this week and said "how much extra" £1 says me she didnt mind at all and was happy to pay it.
I spent 25 years selling cars and beleive me when I say the more you do for free the more they expect it as standard and whether its selling cars or window cleaning people are people are people. I NEVER EVER do anything for free as they then expect it every month ..... the only time I did do summit for free was an old dear and her daughter asked me to quickly mop and squeegee 2 large mirrors in their kitchen after I finished their windows .. no problem says me they said how much extra nowt says me .. have a nice day ........... goes next month finished the windows and knocks for payment " you havent done the mirrors yet" ... now they expect it as standard every time I go and now too late to charge them for it. I learned my lesson.
Soon to do a review of my pricing when I go WFP and will start asking whether they want their doors and garage doors doing either that or work it into the quote and say summit like "£14 and that includes all the doors and your big garage door" if they accept then happy days but if they say summitt like "HOW MUCH" I can respond by dropping to £12 but no garage door etc etc.
Only so many minutes / hours in a working day I firmly beleive if you want to have a good living with window cleaning then you must run it like a business and charge people accordingly for what you do for them ... I dont feel guilty as ALL customers have the potential to turn bad and drop you so I dont want to be their friend just to supply a good service at a fair price