As Mark (Flexi) said it all depends on your market, that's if you have one of course!
I have a few staple customers that always go for Fountain, then I sell hardly any slimline pens (Cross ballpoint) never sold a single slimline at the craft fairs on the lead up to Christmas yet sold RB' and FP's. again, it's where you are selling and what people want at the venues.
Then again, I would sooner only sell one Fountain pen a year for £200 than 20 cheap ball point pens for £10 each just the way I see things.
Sorry I can't be more helpful on that one for you.