Watching this thread develop - so we all know that you're going to be buying stuff.....lol.
Since you recently missed the group buy on taps and dies, finding a good alternate will help. I suggest two different places for lots of tooling needed by custom pens - drills, taps, collets, etc. Victor Machinery
Victor or SHARS Tools
Shars are good sources. I've used both and highly recommend them for anything 'machinist'. Beaufort in England
Beaufort is also a good option for you since you don't have to deal with the crazy environment going on here in the US with tariffs and associated silliness. They sell excellent mandrels, pen components including blanks, and some pretty well made kits if you are in the mood for a kit. Be sure to also check out Phil Dart's Pen Instruction PDF on the site - it's well written and informative
Phil'sPDF . Turners Warehouse resells a lot of their stuff as well as some good tooling made and developed by Jim Hinze
Hinze Pen Tools. There is also fellow IAP member Rick Harrel who makes REALLY nice stuff at a great price. His pricelist is in the Vendors forum here.
I agree with the above comments on starter vs bottom taps/dies. Most resins we use don't require a 'starter' tap, and if you use non-opaque blanks, the bottoming taps look cleaner. Save some cash by reducing the tooling costs.
Hope some of this helps!
Kevin