10 ft or so is about the right distance for midfields - a little more a little less.
It's going to be difficult to find a decent pair of midfields for less than a $1000. I'm big on suggesting kits for getting the most bang for you're buck. All you need is a soldering iron and a screwdriver. Here are a few in the $1000 range that would make excellent midfields. You'd have to spend many thousands to get better.
Cool, thanks for the links barefoot. Im also curious about the dynaudio BM15s for midfield use, it is in the same price range as well. Or would it still be better to invest in one of those kits?