Blimey hope you have deep pockets
Chisels
grinder(to sharpen the chisels)
pen mandrel
mandrel saver
chuck complete with jaws
drill press if you want to drill off the lathe
pen press to assemble or suitable clamp will do
pen kits
pen blanks both wood and acrylic, corian can also be used
finishes and glues
That is just a basic short list and I am sure someone will add to it
Don't forget a good sense of humour