Its 1 dollar per foot!
Only charge for the 1567.5 ft
So that would be about 1,567.50
However, it being a larger job i would see giving a discount, maybe 10-25% off of the normal residential price.. since residentials at most might have 400-600 foot of gutter, and wow thats a big house!
I think if it were me doing it, i would tell them its 1.00 a foot 1 story and 2 per foot 2 story, but since they have a large amount of gutter needing cleaned that you will do it for 75c per foot! And see what they say, it never hurts to ask.
Also you can notice the way or what they say after you say its 1.00 per foot, and they might say ok, do it!
However tell them, you have 1567 foot and its 1 dollar per foot, pause to see reaction, then if you feel you need to sweeten the deal, say promptly, like you didnt pause

, However ill do them for .75 since theres so much.
Well, if you go this route, remember that confidence in your pitch will determine a lot too. If you dont get it or you have to go even lower, please consider how much time it will take, you want to atleast make 35 an hour i guess.
And let us know which way you went, also if you got it or not.
If they decline, say " well how much were you planning on getting this for?" if they say oh idk but not that much, say well i might be able to negotiate a little but you have to talk with me about it, and make sure to let them know after they say, "well, we'll give you 50c per foot", You say - "Let me take another look at the job and ill be right back in" That gives you a chance to make sure you can make money still, and also if you cant make money there, to come back in and say no im sorry the cheapest i can do it for is going to be 60c!
Again, its all about your "negotiating"!