Something like the VR4 is an entirely different ball of wax. Older cars can be beasts. I've personally been astounded by a well-prepped Porsche 914 on a track. A couple grand and a lot of sweat and grease can add up to an attractive machine. But it's not the turn-key solution that a newer car is.
If you really dig performance cars, there's plenty of them out there, with lots of available upgrades, under 3 grand. Miatas, older Mustangs, older Camaros, DSM cars (Laser, Talon, Eclipse), Supras, etc., the list is endless. If you're willing to hack into one, you can produce one heck of a fine and cheap sportscar. If you've got the desire, pick the one that appeals to you and go for it. But that is miles away from the reliable everyday transportation you can have with a relatively new car. They're really different classes of fun. Those are hobby cars, not every day transportation for mature adults who actually need to get places.
And that's not to say it can't be day-in/day-out reliable.. because they can be. But they will always be a bit tempermental and you will always have to be up on the maintenance. They aren't "turn the key and forget about it" types of machines. So if you're going to go that route, love the car you choose and make it a part of the family. Drop the 3 grand, in the car that's worth $2500 from time to time.. because you love the car and it's an extension of you, and it serves you well (if you take care of it, it will!!!). Ultimately, all cars cost money. There's no free lunch. Over the extended life of your car, eventually that $3,000 car will cost you about as much in service to keep it running as the $30,000 car. It's not savings... you keep it because you like it.. and because all cars cost money. Find the keeper... The one that speaks to you. Or else just buy something newer and somewhat disposable.
In that range of economical enthusiast cars, I'm actually a fan of Corvettes. 20 grand buys a nice used Vette. Used as a daily driver, the big honkin' V-8 engine lasts forever, it also keeps its collectible value on the used market quite well, it is an impressive performer, And the aftermarket for them is huge. Insomuch as an car could be considered an investment, vettes are good ones. Kept in good condition, they don't lose their value much below $20K. They are good performers, great lookers, they are reliable, and people know a lot about maintaining them and keeping them in good shape. But on the down side, once you drop $20K on a vette, you may still need another daily vehicle for the days when the vette is out of commission... and your budget is now getting tight. It's probably not the car for you, given your stated interest, but I bring it up to give you an idea of what older performance cars (like the VR4) give you, and what they require in return.
IMHO a stick is the only way to drive :rockin:. In the BMW line I've had a slush box, my M3 was SMG (before they double clutched them - and I'd probably never do another) and two 6 speeds. 
