Kenny

The direction you choose may require different options on the Mill you choose.

If you are looking to make it a full time job, you would want to get a more durable Mill with hydraulics and maybe setworks to help improve production. If you are going to be supplying builders with custom posts and beams that are 25 feet long, then you need to make sure you get a Mill with a bed long enough to accommodate them.
If you are going to be doing this as a hobby or part time, you won't want a $30,000 Mill sitting around while you are at work, as you won't make enough money to make the payments...

In a nutshell, determine as close as you can what you want to do, how you will feed the Mill, how much you will make, then find a mill that meets your needs at a price that won't dog you.

Hope that helps...

John