I have the 24mm f2 and I really like it, the extra stop of speed is great. If you cant wait the 2.8 is very well reviewed as well, but if you check the auctions the f2 does sometimes drop below your price point of $200.
just recently one sold on the bay for $177 from calumet on the 29th, BGN grade it seems. I bought mine a few years ago for ~$180.
Its my go to lens on the street, the dof as with all wide angles is great, so it makes subjects that much easier to keep in focus, more so than the 28mm or 35mm.