I normally don't recommend cheap tools, but here goes anyway...

Four years ago - in a pinch - I bought a 4in angle grinder from Harbor
Freight for around $19. I subsequently used this tool to do a huge
amount of metal cutting on an old Mercedes I restored. This job
entailed hour upon hour of cutting, sanding, and wire wheel work using
that little rascal. Since then, I've used the same tool for scores of
jobs including cutting all the rebar for the foundation of a house
we're now building. Like the Energizer Bunny, this thing just keeps on
going. It hasn't even burned through the original set of brushes, but
HF tossed in an extra set to cover that eventuality. This is one tool
no shop should be without. Be careful though, it's an easy one to get
hurt with. I heard of a guy setting one down on the bench while it was
still spinning, only to have it whip around and slice open his gut.
Thrown debris and exploding cut-off wheels are also par for the course
- wear goggles or a mask and work gloves.
Richard Johnson PE
Camano Island, WA