If you want a two-barrel pen, then my recommendation is the Jr. Emperor rollerball pen kit, available at ExoticBlanks.com :
The Jr Emperor features the same fine detailing as the Emperor, but in a smaller size. It features the same durable plating and unique and intricate hand-carved patterns that have been richly coated in jewelry-grade rhodium and Black Titanium.
www.exoticblanks.com
I like the styling and appearance of the Jr. Emperor much better than the pen that you show above, which I think is the Jr. Majestic.
You might also consider the Jr. Statesman and the Jr. Imperial (if it is still available). . There is also a Jr. Lotus.
The Dayacom website may have a few others but it is not a particularly easy site to search and you would not want to buy direct from Dayacom because they have a minimum order quantity (MOQ) of 100 or maybe even more.
If you want a single-barrel pen, then I have two suggestions.
The Electra (screw cap) :
https://www.exoticblanks.com/electra-rollerball-pen-kit-gold-and-chrome.html
The Zen (magnetic cap) :
https://www.exoticblanks.com/zen-rollerball-pen-kit-chrome.html
Other plating options are available.
All of the suggestions above are quality kits, in my opinion.
With regard to the Electra, rather than putting a 0.3 degree taper on the barrel by turning bushing-to-bushing, I recommend that you do the barrel perfectly straight (sized to the larger of the two bushings at the nib end). . This results in improved appearance and easier turning.
EDIT: . I nearly forgot. . In the intermediate price range, consider the Jr. Antony (sometimes spelled Anthony) and the Jr. Aaron - both 2 barrel.
I think ExoticBlanks has both of these. . Could also try ....
www.beartoothwoods.com .... or ....
www.turnerswarehouse.com ....