this is an estimate for 1 window unit
the unit itself has 6 sides approx 1.25m wide x 1.75m tall and comprises of a top glazed panel to be cleaned in & out, also the lower panel cleaned in & out plus in between the glazed panel were the blinds are situated, these lower panels open up to allow accses to the inside but and its a big but they open outwards :

So in total 6 side of glass
Now these glazed units have paint & varnish etc on them and a serious amount of limescale or whatever has built up over the last 20 odd years so will need a serious amount of elbow grease and not to mention MDR & crystal clear on them,
I estimate atleast an hour on 1 unit to get it clean how much would you quote for this 1 unit