I was charging $6 for outside only while my in n out was $10. I have sinse rasied my prices where now $12 per window and $7 for outside only. The issue is like you stated. You still have to go inside. I dont mind at all. But it is a bitch. For a repeat service every other month I would go down as low as $5 or even $4 per window depending on things. If the customer was willing to remove the screens the day before I show up I would go $4. I would also sell them on the fact if they went this route they would not have to be home during the cleaning and thus would not have to take a day or 1/2 day off work every 2 months.
I too, price outside only at 60 - 75% of full job…It cost money to staff and equip a truck to get to their door…whether I clean 10 windows or 50…it is still a trip.
I do have some really good customers that I do quarterly and have referred many of their friends and neighbors to me…I will make special deals…and throw in a few freebies