@ the OP

If you don't mind single speed instead of fixed gear and you have a Fairdale dealer in your town (there is one available on ebay if you fit the small/medium size though), the Fairdale Flyer might be right up your alley It's under $500, it's steel (albeit hi ten), and it's got fat mountain bike tires right out the box. Just FYI, I haven't ridden one or anything, I was just recommending based on the specs of the Flyer and what you said you wanted out of a bike.