Established hosting companies often offer dedicated server plans that come with management. The management fee is very affordable. Unless the company you engage with wants to keep their company data highly confidential, then hiring their own team of server and network engineers are much preferrable.
There are many hosting companies that host their servers in US data centers. Go to hostadvice, and filter the hosting companies based on data center location in US.
The next step is you want to test how supportive and how reactive is their customer support.
Most of the hosting companies will claim they have 99.9% uptime. You can validate this information via Hyperspin.
Then negotiate a deal that works for you. How much percentage are you getting from each recurring sale? What are the terms and conditions for your clients? Any contract, upfront payment or hidden fees that you should know?