Well, I have a lot of friends into very nice cars (it's SoCal, after all).
Here's a quick review of some fast cars that I'm familiar with that should be in your price range.
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Audi TT: Friend used to have the non-S, non-Quattro version. The 1.8T engine is a very, very good engine. Especially if you're willing to spend a little money on modifications - can make it a lot, lot faster. Wouldn't recommend the TT though - has bad driver visibility, and is very small with a virtually worthless back seat. Take a look at the A4 instead. Also, the Quattro is heavy, expensive, and increases drive train power loss - don't get it unless you really think you need it.
Audi A4: Great car, a real bargain. Check out audiworld.com. You can get a low end one for cheap (~$24k). Get the 1.8T - very reliable. Don't get the quattro. Don't get the V6. Don't get the sportmatic - get a stick shift. Very luxurious, especially compared with japanese rivals. Easy to modify. Good warranty. Very stylish. Overall, a great car, especially for the price. Very safe. I know a lot of people who have totalled their A4's - and walked away without being hurt. Has a lot of airbags and good overall design.
Audi S4 (used): Crazy fast, and light. Know someone with one that runs high 12's STOCK. No joke. But, not very reliable. And, over your price range. From what I've heard, Audi has been losing money on this one with engine and turbo replacements. Stay away unless you're really brave.
BMW 3-series: Don't bother unless you really want the BMW badge. Nice cars, but not a good value in comparison to the A4 and others.
BMW E46 M3 (used): Has real engine problems. Have a friend who's father is a BMW Shop foreman, and from what I've heard, I wouldn't recommend buying one, even new. Not as fast as the STi.
Infinity G35: The coupe has near 50/50 weight distribution, and corners on a dime. Very stylish and fairly fast (mid 14's, I believe). Not much can be done to modify it, but - who cares. Good value. Nicest seats available in any car, IMO. Great for an every day driver. I wouldn't wait for the AWD - it is so well balanced, it doesn't seem like it would be a big help. Oh yeah, very safe. My good friend wrapped his around a telephone pole and walked away without a scratch. By all rights, he should've died. Good thing for the excellent design and huge number of air bags.
Nissan 350z: The G35 coupe is a better value. Seriously. Get it instead.
Subaru WRX: Cool car. Very fast. Can be made even faster with mods. The STi is very quick (faster than an M3). But, if fast is all you're looking for, buy a regular WRX and throw on a monster turbo. The STi doesn't seem like as good of a value as the Evo. Had a friend with a modified street WRX that ran in the high 11's. Great car, until it lost compression in a cylinder. From what I hear, they have some engine problems. Also - insurance is HIGH on these.
Mitusbishi Evo: Cool car, fast. Not a bad value. I vaguely know someone with one, but haven't actually spent much time with one to say much more.
Volkswagen GTI: Super nice car. I hope to buy one in the next year or so. Can be made very fast. The 1.8T is a great engine (read above Audi posts), easy to modify, and can be made to be fast. (A chip alone can add a LOT of horse power thanks to the turbo) I don't think I'd get the R32 - all wheel drive = drive train loss + more money. Plus, the VR6 is not as modify-able. Also, the 1.8T is lighter = better cornering. Look into a 20th anniversary GTI - great value. Good warranty too (4 year, 50,000 miles + roadside assistance + other goodies).
Dodge Neon SRT-4: Fast. Cheap. Seems like a steal. I've heard stories of people dyno-ing their SRT-4's, and getting insane wheel HP - STOCK. I've also heard that they can be very fast - more so than average - if you get the right one. Way under your price range, and not a very luxurious car in comparison to the rest, but hey, it's worth mentioning if you like fast cars. Probably not very safe compared to others.
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That's all I can think of for now.
My recommendation:
Go test drive the G35 Coupe, the A4, and either the WRX or the EVO. Pick the one that you like most.
If you want a fast car stock, maybe the WRX or EVO is for you. But, they're kind a small.
If you want a more luxurious car, better looking car, look at the A4. Especially if you're willing to do minor mods like a chip.
If you want the best daily driver and overall nicest car, look at the G35. Not really modifyable, but man, it is a sweet car.
Good luck!
-- Rob