After considering epoxy and cement-based leveling for my shop floor, I'm now thinking maybe all I need is to grind it and seal it. I can rent an Edco 2-wheel grinder locally for $150/day. I figure I'd need to remove about 1/8" on average over the 400 square feet to get it as smooth and level as I'd like. The manufacturer says this grinder can remove 1/32" over 350-500 feet per hour grind and seal. Four-plus hours of grinding sounds like a bit of a slog, but if it turned out well, probably worth it. I got 'resurfacing' (grind, level, epoxy coat) estimates from $4.50 to $7.50 per square foot. Anyone have experience and advice about grinding concrete floors?