The old Unimats were high quality machines. I don't know anything about the current Unimat products but they look entirely different. You might want to look at the Sherline product line - they have small lathes & mills and attachments to mill using the lathe. These machines use lots of aluminum and are very light so aren't super rigid but they're fine for hobbyist use. For more rigidity (and weight) you could look at a MicroMark lathe.
I've used a small Sherline lathe/mill for years and it's handy to have around - very good for spacers, oddball washers, collars, etc. It cuts plastics, aluminum, and brass very nicely. I've cut some steel with it - time consuming but it'll do it. They'll even do threading and knurling with attachments. Accuracy isn't great but you can hold about .002 without much trouble. The machine itself is easily moved, weighing only about 20 lbs attached to a base.
Both MicroMark and Sherline have excellent web sites and a full range of tooling and accessories. Plan on spending at least twice the machine's cost on tooling. Also, be sure that the leadscrews are "inch" rather than metric if that's a consideration.
Warning: These machines introduce you to a whole new set of hobbies. Plan on spending a ~lot~ of time just playing around.