I'm not going to suggest a price. However, I will suggest the following for safety as some balconies would require a long ladder. If you can't get a brush through the balconies (is there glass or meshing there?) either submit a quotation leaving the bottom of the balcony doors: OR ask Alex G if it's possible to make you a special gooseneck n an "n" shape. It doesn't look like there are any balconies higher than 2 floors above ground so should be manageable to clean like that. Obviously such a tool will cost so price accordingly, explain the situation and that you are quoting for the first "x" number of cleans in order to cover the cost of a special tool or quote high just on first clean to cover it. It's the sort of tool that will rarely, if ever, be needed elsewhere so it's right that their job should cover it IMO. I did similar once with ali poles and two goosenecks joined and that was a ballbreaker - so it should be fine with light carbon.