You are right about your comment about craiglist website but craiglist ad posting service is not new but different people that offer this service charges different prices,how much do you charge per post and how many can you post per day?
I can Post 5 to 10 ads daily and i charge between 3 to 6$ per ad depending on the requirement.
I will use my own Paid VPN / proxies. Also i will verify each Ad by a USA Phone number.