OK, Theo! You asked a lot of questions. First, there are adds on a couple of boards selling used Dillon 550Bs. Check out Tom Bower's reloading board at www.subguns.com.
Also there is a note on Tom's board about a 550B being sold (or more precisely, auctioned) on e-Bay. Don't worry about buying Dillon equipment used because Dillon will stand behind it's products forever. I know there is somebody who is discounting Dillons a little and I'm sure somebody will give you that info. One thing I would suggest is getting the video tape from Dillon on setting up and using the 550B. I found it helped a lot and I still go back and refer to it from time to time (I'm not techincally oriented and think tech writers write in circles).
OK, to get started you will need the following (besides the press, caliber change, and dies)
1. A good reloading scale. Everybody sells them and they are mostly all good. If you are going to reload, you need to make contact early on with www.midwayusa.com,
They both sell components and about everything else.
2. The next thing (or really the first thing before the press) is a good reloading manual. The powder manufacturers all produce booklets which give loads for (surprise, surprise) their company's powder. Get a manual produced by a bullet manufacturer like Speer or Sierra....they both have good instructions on the art of reloading.
3. You are going to need a place to do it. Try to make it a dedicated bench so you can store all your things. You will find that you will begin accumulating powder, primers, projectiles and a whole assortment of other things.
4. Finally, make sure you have safety equipment. Saftey glasses (or prescription safety lenses) are a must, and ear protection wouldn't hurt either.
I'm sure I have left some things out. The others on this board will jump in and let you know. You will find that reloaders are a friendly lot, willing to share knowledge with their fellows.
Hope this helps, Mikey
PS: Almost forgot. Make sure you use taper crimp dies on all your automatic pistol cartridges to give them a good, snug, factory crimp.
When Guns Are Outlawed, I Will Be Another One Of The Quarter Million Violators Who Are Not Prosecuted
[This message has been edited by TheOtherMikey (edited November 11, 1999).]