I have owned and operated a portable one man sawmill for almost 20 years. Durning that time I have looked at all different kinds of bandmills and circular saw mills. I have a circular mill, and they do have a wider kerf which makes more sawdust than the thin kerf band mills.
There are band mills to be had for around $3,500.00. Most of these are very manual, you have to push the band through the log much like oy would with the chainsaw powered one's. A band mill can cut consistant size lumber provided you follow the rules. You have to have a blade that is sharp on both sides of the teeth. Just like a chian saw will cut curves, a band saw will cut to one side or the other if the blade is dull on one side. This usually happens if the logs are a little dirty.
If you push the band too fast through the log it will force the blade to twist, then it starts going up and down, or maybe just up or down. Circular mills tend to be more expensive, put a little more log into sawdust but will tolerate a little more dirt on the log than a bandsaw will. Bandsaw mills tend to give you the option to cut wider boards than a circular mill.
I have a Mobile Dimension Saw, they have a website I think it is
www.mobilemfg.com
If you have the time custom sawing can be a profitable business. I have customed sawed as a part time job for 15 years. I turn away more work than I can do almost every year. If this is the only building project you will tackle for a while then it will make more sense to buy the lumber you need. But, if you have other building projects in the future and can afford a mill now you will use it more than you think.
I enjoy the Sawmill and Woodlot magazine also.