I was asked to quote for a council property. I turned up; a fairly big place; I counted 130 windows (or units of windows which is my own personal measurement).
It's fairly easy access, local to me, so I wanted the job, but being council I didn't expect them to want to pay much.
So I said £250 every-three-months and the manager said 'Yes, when can you start?'
I've got to supply R&M statement, plus insurance (which isn't a problem), but I walked away thinking I wish I'd charged £300.00.