It's like we tell newbies that want to build an airplane. Define your mission as closely as possible before you even start looking at stuff. Once you have a definition of the basics, then add the must have's and the would be nice to have's. Once you have this, then you can start to look around for equipment to fit your needs. If you are only going to machine soft materials for parts that fit into your hand, then there is no real reason to be looking at a K&T #2 when a Clausing 8520 or Deckle FP-1 will more than cover your needs. On the other hand if you are going to be working on stuff half the size of a refrigerator, then the K&T #2 is going to be way too small and you need to thinking and planing for something like a VMC-150.
In my case, I can make almost everything on BP #1 and have room to spare, but I do have some upcoming parts that would be a challenge on a VMC-150,which is probably too small, even with a 36x61" table.
So to wrap it up, define what you want to build for most of the time, then add some growth room, and determine the materials you will use the majority of the time and the necessary speed and feeds requirements. Also determine available power and space in your shop. Armed with all that information, you can start looking at various sized mills and from there, bide your time and keep watching for one that will do the job and be within your budget. Also, don't forget to budget for a vice, and clamping hardware and a selection of tools.
