A table saw will be quite helpful as well, but you can make a simple straight cutting jig for a hand held circular saw. If you use that and take your time, you can do really well with a hand held power saw.

I recommend the Rigid router at Home Depot that comes with a fixed base and a plunge base for $200. That is enough router for some pretty big jobs, and the fact that it has both bases makes it VERY versatile. You can make a circle cutting jig for it from plywood for a couple bucks, or free if you've got a piece laying around. I've used such a jig to cut the cage rings and a mirror blank for my current project, and they are perfect.

-Brian