Alistair,
Sorry, I didn't mean to be rude. As to how much you should pay for the list, only you can know that as we don't know what it is you're paying for, and neither do you until you investigate, but I wouldn't pay much because if it hasn't been done for a while a lot will have found someone else, in reality you'll have to re-canvass them all but with the added bit of help that you can say "I've bought the previous man's round, and I've come to see if you would still be interested in having your windows cleaned."
Regarding traditional tools, if you're employing an experienced trad cleaner, surely the best thing would be to ask him what tools and equipment he needs? After all, the reason you've employed him is because he knows, and you don't.