Check out Little Machine Shop, Tormach, Smithy, Taig and others for prefabed units.
For going the DIY route you are in the right forum. Check out the section you posted this in closely. There are many options but I'd suggest checking out the various G0704 threads.
Depending on what exactly you are trying to do and in what material you may find the spindle speeds a bit slow on some of these mills. Research a bit before you buy.