If Dan is to make a go of this he realistically needs a good mover and the harsh reality is that whilst the Roman Harvest is a great kit David Has got that kit with that price reasonably sown up. Whilst we all like the RH, its hardly a fast mover and Dan needs volume to pay for any tooling and to generate sales outside this forum world - most woodturners who make a few pens turn a few slimlines and thats it, the transition to RH is unlikely to occur.. The one hole in the market that sticks out like a sore thumb is a good quality pencil. most of them are total crap, I have found the bodge it refill from TB to be very unreliable, I no longer sell it, be it very briefly at the outset. The Vertex is a cracking pencil but limited in its appeal as the design is very masculine and overall it isnt very elegant. So as a design brief a good quality 2mm lead pencil, clutch mechanism, that appeals to both male and female at around £6 max per kit, preferably £4 and you've cornered the market.
Fountain pens and rollers, cross fingers if the copy is good and the threads smooth, I'll have the first 100 please Dan!!! Gold Chrome and Gun Metal. If you have a choice of developing one over the other, put the rollerball on the back burner and launch the FP first.
If you really want to develop a top end pen then the nouveau sceptre is a good pen for half the retail price (where it should be priced if it hadnt been for horrendous design royalties pushing up the price), you should be able to bring the price of this one down to around £10 a pen where it would be very attractive and probably a reasonable seller.
That's my sixpenny worth.