Today there are many small saw mills available, most of them band mills. The correct mill for you depends on several factors.
What type of wood are you primarly intrested in sawing, softwood or hardwood?
What size and legnth needs will you have?
How much do you want to spend?
How much do you plan on cutting per day?
How long do you plan on owning the saw mill?
How portable does it have to be, will you bring the logs to it or it to the logs?
How will you load the logs onto the mill?
There are many portable band saw style mills offered today starting around $3,500 all the way to $50,000. There are several rotary mills offered today which if I remember right start around $8,000 and go up to $25,000 or so.
Lucas makes an impressive rotary model that I believe is the least expensive. It is all manual neaning you have to push the saw through the log like many band saw mills. I watched one cut lumber and it did a fine job. The log rested just about on the ground making log loading easy.
Most band saw mills are similar, the carriage runs along a track. Some have power feed and some are hand feed, depends on how much you want to spend and how much you intend to cut in a day.
I have a rotary that I have owned for over 20 years made by Moble Manufacturing Company. It has worked well for me cutting a mix of soft and hard wood.
If you plan on doing a lot of cutting with a band mill consider buying an edger to go along with it. The log loading options and power feed are nice too.
Best thing to do is visit a few people who have a small mill like what you want and watch them operate it and ask a few hundred questions. They have to be easy to adjust and operate. Saw dust build up on the track is one of the things to look for as this will cause an inconsistant thickness.
There are several different types of blades and teeth which make a difference cutting hard, soft, or frozen wood. There is a lot of good imformation out there, good luck.
Randy