I'm new to the Parker pens and am curious as to the differences between the Parker Lucky Curve and the Duofold. I see the Duofolds fetching big bucks on ebay but the Lucky Curves not so much. I have an opportunity to purchas an unrestored (but in good shape) Lucky Curve but am not sure as to what i should be spending. My intentions are to restore the pen and possibly resell. What do the restored Lucky Curves usually go for? Also, any recommendations on how to properly restore the filling system if needed?