Well jff, if you wait for the right moment most of the times you buy DVDs for a fair price, you just have to be patient! 

As I already told you, Serenity looses much when you haven't seen the series, my advice to you is to watch firefly (I can borrow you my series box if you want to) and then watch Serenity again.

Right now Firefly is borrowed to jps, maybe he can tell here what he thinks of it(unless he's too busy programming in .NET).