Most guys are around $1-$1.50 per linear foot. We'll usually run a fall special...single story homes $89, 2-stories $129. Plenty of people are cheaper. I'll match any price if the customer can obtain proof of workers Comp ins and liability insurance from the lower bid.
If you're taking down gutter guard, you'll want to know if the old guards are screwed in or otherwise attached. If you only have to lift them out, you can pretty much throw them to the ground as you're cleaning the gutters by hand. They really shouldn't be much extra effort.
If you have to unscrew them, it could take several hours. Charge accordingly.