I found an interesting thread on Weldingweb called "tools from Harbor Freight that don't suck".
I think we'd all agree that their tools are not high quality, but what about when you just need something light duty for a short time? For instance I bought a diamond blade wet saw to do a bath renovation for about $50 - less than I could rent it for. It worked out just great for me. I also bought a 4 1/2 inch grinder for $15. Heck, if it worked for one hour I'd be happy, and so far it seems just fine.
This might be an interesting subject to explore since the welders site concentrated on metal working tools.