How can I buy a license to use with CF9

I have a client that needs a CF9 license for an additional server.  I know you Adobe doesn't sell them any more.  The cient is willing to buy a CF10 license, but they need to be able to run a licensed copy of CF9. 

I just had a chat with someone at contact support, who assured me that there was no way to apply a CF10 license to CF9.

I've got to believe he was misinformed.  Adobe has to know that CF customers don't upgrade the instance a new version comes out and may need some more licenses before the do.