My experience has shown me that the fastest way to 'properly' clean out the gutters is to get up on a ladder and clean them by hand. I have used the blower attachments and they make a mess like no other. Especially if the gutters are wet. You'll find yourself cleaning off the roof, house, windows and yourself.
I charge $.50 per linear foot with a minimum charge of $45.00. Depending on your costs, overhead, dumping fees, etc...your price will differ depending.