I guess the most important thing is to get a quiet tire with good tread life that is cheap. I just don't want it to get me killed in the rain!
again, that's asking a lot, especially for that price range.
i've had good experience with the Yokohama AVID V4s and YK500 (or the like), as well as the General Exclaim UHP (not sure if it's available in OEM sizing, i had it on my old 18"s)
On my old 525i I ran H-rated Toyo Proxes TPTs and really enjoyed them. Weren't terribly loud, good grip, and had something like a 60k mi treadwear guarantee... It was something like $110 mounted per corner including free front end alignment and lifetime road hazard protection/rotations/snow tire swaps. Might have been less, don't really remember as it was around 04 or so.
When I need tires on my new-to-me 96 LS400 I'd buy TPTs again.