While I find C's response unnecessarily harsh, I have also wondered about such a program. But, really, even though it's expensive I think it's worth going through the actual program. It will give you more credibility within the field. Also, for all the money you'd spend on an accredited progam online, you would be much better off actually completing a workload.
I also plan to opening a joint degree with Art History. If you do find a satisfactory progam do let me know!