This is what I use. The * is required. The others are nice to have and makes the job a lot easier.
* Pen Kit $5-$20
* Pen blank $0-$15
* Saw to cut pen blank to size (I use a chop saw)
* Pen Makers Bit Set $30 or individual bit for pen tube size you are going to make
Self-centering Pen Drilling Vice $80-$100 (or make one)
Pen Tube Insertion Tool $11 or use a dowel or pencil
* Medium CA glue $8
CA Accelerator $12 speeds up the drying
CA solvent $8 helps to unstick things, especially your fingers, and to clean up insertion tool
Pen Mill Set $35 for milling the wood even with and 90º to the tubes or use disk or belt sander
Pen Mandrel $23 or learn to turn without mandrel (I use a mandrel)
60º Live Center $20 you will have less wobble and will make your mandrel last a lot longer.
* Bushings for pen $5-$10
Turners Sandpaper Pack 120-600 $15 or use what you have. I sand to 600
Finishing supplies such as CA, friction polish, buffing system, Poly, Micro-Mesh, etc
Pen Press $50 or drill press or wood clamp
Pen Disassembly Kit $15 for when you screw a kit up and need to take it apart.