But still: how many quotes did you get before signing this contract???
And you're looking at ~$2800 bucks for retail cost of the siding. I'd get a price breakdown of what this company is charging, because more than likely, he's charging you in the 4-5k range for the siding. The foam insulation board shouldn't be more than 1k.
Honestly, for that work, I'd estimate it out at 16-18k including cleanup.