IMO
Turning pens is like anything else, you can go as cheaply or as expensive as you want.
Mandrel, I prefer a standard no frills mandrel. if I need to adjust for length, I will pact the extra space with an tube or bushings to achieve proper working length.

Drill Bits, I started with a PSI bit and it worked fine for many pens. Once it dulled to the point of replacing I opted for a Colt brand. I have heard that the Fisch is supposed to be very good and less expensive.

Barrel trimmer, For a while it seemed it didn't matter which one you bought, they were all the same "junk" having to apply way too much pressure to get them to cut and they dulled quickly. I have upgraded to the (more expensive) Whiteside barrel trimmer. It's like night and day.
Links are what I have, you decide whats best for you and your situation.
Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to or
Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to or
Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to or

A lot of this depends on how and what you turn, I ONLY turn wood, no acrylics or man made materials. There are special bits and methods for those products.

One other thing, if you can, when turning 20 pens I would build them in large batches, at least ten at a time.
Do all the cutting, all the drilling, all the gluing etc, in an assembly line method, it will save you time overall.

I only linked to the 7mm bit because it's the most common with the sets most of us start with.
Like I said it really depends on how much into pen turning you get.
If you go to a site like Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to or you will see all the different kits available. Within each style it will tell you what size bit and what bushings you need for that style. Some bits, like the 7mm, are good for many styles of pens and other small items.
I've done the "pens for Christmas" years ago, they are always a hit.
Here is a (poor quality) photo of a portion of what I turned.

Ken,

I turn lots of pens.  I really enjoy being able to see the finished product in a short time.  If you want to get started right, pick a PSI kit you like and order the sampler set.  You'll get 3-4 pen kits in different finishes, the proper drill bit, and the bushings for the kits.  That takes the guess work out of it and you don't wind up with a set of drill bits you never use.  I recommend you start with a single barrel pen like the Knurl GT (with or without stylus), the Executive, or the Gatsby.

As for mandrels, I agree with Ed.  I like the standard A mandrel.  There is also a B but not many kits need that one.  I also recommend a mandrel saver which is a life center that fits over the end of the mandrel and rests against the bushing or spacer.  It keeps you from putting excess pressure on the mandrel with your 60 degree cone live center and causing it to bend and throw your pen out of round. 

+1 on the Whiteside barrel trimmer.  I have to sharpen one of my trimmers every dozen pens or so. 

One word of warning, pick 1-2 pen kit suppliers and stick with them.  Just about every supplier carries some of the same basic kits, just with different names (Sierra, Gatsby, Wall Street, Mesa ...) but they're not all the same.  Bushings may or may not be interchangeable.  Quality is not the same either.  Pick a few to start and you'll be happier.  PSI puts out 1-2 catalogs a month.  Beware the vertex.

Enjoy.  It's a lot of fun.

Thank You Steve and Don, I was hesitant to ask my initial question because I know this has been covered, but Im glad I did now, you guys and Ed and have extremely helpful.

I ordered the A mandrel,a live mandrel saver and the whiteside barrel trimmer set yesterday. I also got a set of fisch bits, they werent cheap but Ive been needing bits for awhile and have just been putting it off.

I will head back to PSI today and may just get the sampler kits to start with.

Thanks for all of your help

Ken, all good advice here, and sounds like you're on the right track.  I do pens frequently, and recently did a batch of PSI Trimlines, and decided to make a little vid of my small production run, which you can find here: Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to or

I use the mandrel saver as well, works great.  You can PM me if you have any specific questions - rockwoodcraftedpens@gmail.com.

I want to thank everyone for their help and encouragement.
I finally got all my stuff in and turned 3 pens today. I do need to get me a pen centering vise to help with the drilling though. My homemade vise worked so so. I practiced on several pieces of pine before drilling any of the wood I wanted to actually turn. I wont tell how many pieces of pine it took lol.
These are Cedar, Mesquite and Black Walnut. Not a great photo, but you get the idea. Comments and critique are welcome. Be gentle, these are my first 3

Very Nice pens for your first.