I'd be okay at $200. You could have charged a little more given the fact that you were doing an exterior wash as well, but I would be happy at 200 for that for the most part.
I did a full interior on a jeep that had a sunroof leak. Had their clothy-canvas type seats which are nearly impossible to clean with shampoo or a steamer. basically hand shampooing the seats, tornador the headliner, and shampoo the carpet. I charged them $120 and it took me about 12 hours. I got my butt kicked but it turned out so much better and I really wanted the job to prove to myself what I could do. I did, however, underestimate the amount of work involved (due to me thinking I could just use the shampooer like normal on the seats and carpet.)
Interior never looked 100% but it was probably as good as it was gonna get. Drivers seat still a tad bit wet so it still looks a little bit dirty in the pics.