he is trying to scam you, so definitely don't pay that. your original verbal contract is $45 / hour to hire him and his business. who he hires is them on him. NOBODY conducts business this way by terming it "$45 an hour" and then meaning that applies to everyone.
if you had a crew of 12, you tell the person hiring you either what the overall estimate is (which is how it's supposed to be done) or an hourly that the BUSINESS will charge.
tell him you will pay him the agreed upon rate and hours. if he wanted double that, then it should've been a $90 an hour term. let him take you to small claims if he has to, you are not acting unreasonable. let a small claims judge make the decision.
if you want to avoid court, you could make him an offer over the agreed upon price, but do not agree to double. don't let it hassle you, small claims is not that big a deal. but be firm about it, tell the guy either (1) take our deal or take me to court, or (2) offer him a slightly better than the original deal but significantly less than what he wants. that's my advice.