Definitely targeted at the enterprise, but it's entirely possible to provision and operate a single instance without any kind of enterprise-level agreement.
I ask about OS X support as the requirement for OS X to run Xcode kills a lot of iOS development workshops as the cost is to high / device availability is low.
Thanks again for taking the time to answer.
The standard, and original, is: https://macminicolo.net
I'm sure there are others.