I know harbor freight stuff is pretty crappy sometimes. I have gotten some decent stuff and some real junk. But for $10.99 you can get a 4 1/2" grinder, a 10 pk of cuttoff wheels for $3.99, and a 10 pk of grinding wheels for $4.99 and it works well on cutting the metal. I also have an air nibbler that leaves little chips of metal absolutely everywhere and get stuck in the bottom of your shoes and is extremely annoying. I also have an electric sheer that works well on 18 gauge but is harder on 16 gauge because it rolls up a strip of metal as you cut.
Best bet if you want to stay on the inexpensive side but have a tool in your garage after is to get the grinder.
I had picked up 2 of them so I could have a beater throw away and give my father one. I have a brotherinlaw that breaks just about everything so I told my dad to loan him this one instead of his makita if needs he one and I wanted less wear and tear on my makita for some jobs. Turns out they work pretty well for cheapos.
Just keep an eye out for when they are on sale at harborfreight.com or if I see them on sale in a catalog I will post up the item number for you. Very handy to have.