I have
As of Summer of 2017, Which is after this was initially asked) The developer and the app producer name must be the same. Thus just have them spend the $99 a year and get a Dev account that they add you to to Develop / manage.
Here is a short and detailed explanation: [1]: http://www.goodbarber.com/blog/your-client-s-developer-accounts-vs-your-own-a856/
Here is how to tranfer if already in app Store under your account:[1]: https://support.appmachine.com/hc/en-us/articles/360000012284-Transfer-your-app-to-another-iOS-Developer-Account