24 days work at £80 -£100 per day works out at £2400.00 ish a month , so £1500 seems quite cheap :
That’s appallingly bad for 400 customers and explains the asking price of £1,500. As for running cost of less £2 a week show he has no idea about window cleaning.Having this as a round is a very bad idea, paying or negotiating the £1,500 for the 400 contacts for people who want a window cleaner may be worth it.