That one random CA you quoted costs $267 a year. As far as I can see the requirement is that the CA is cross-signed by Microsoft, and that's quite a large list

That one random CA you quoted costs $267 a year. As far as I can see the requirement is that the CA is cross-signed by Microsoft, and that's quite a large list [0]. I'm only familiar with one of them (StartCom), and that one charges $59 a year for unlimited domain certificates and 1 code signing certificate. [0]: https://msdn.microsoft.com/en-us/library/windows/hardware/dn170454(v=vs.85).aspx https://msdn.microsoft.com/en-us/library/windows/hardware/dn...