dont be scared of older cars, both companies older cars are more tough and reliable than their newer ones. and almost always more of a real drivers car. newer cars in general are watered down and numb... i know of a couple e30's still running strong with 300,000-400,000 miles plus on the stock motor.
with both brands older is better in most cases. you could buy a 5 grand e30 325is and honestly be able to say you have a better car than the guy in a brand new 335. if your looking at m's the older the m3 the better. for your price range you could find an e30 m3 in good condition. they tend to last well over 200,000 miles, but if you can try to find one with lower miles or a rebuilt motor. dont worry about mod's even a completely stock one will blow you away with how well it drives. bmw engineers knew what they were doing, some retard modding it in his garage didnt...
they are pretty tough cars, the e30 chassis is a tank, the motor, while being high strung, is also pretty tough, just dont get behind on regular maintenance. the people that own these cars are people who fix any little detail thats not right. so they are good cars to buy.
e36 m3. while not as much of a true sports car as the e30 m3, its just an overall great sports car. but when driven really hard, it wont be as fun as the e30. both these m3's are the only m3's id look at, the newer ones are just downhill.
if you want something more modern and comfortable, look for an e46 330i zhp. basically a 330i with alot of changes to the suspension, engine, interior, etc.. a really well balanced nice looking car.
if you still want an oldschool bmw, but want something bigger and more comfortable (none of the cars ive mentioned would be uncomfortable for anyone thats not a grandpa) look at e28 m5's.
if you want a sweet wagon, look for an e34 5 series touring. its hard to find a good one for sale, but every once and awhile one awesome one pops up. one sold not too long ago with a completely redone interior, m5 body styling stuff. awesome wheels, completely redone suspension and a supercharged s50 (e36 m3 motor) with like 350hp. join a bmw forum and say thats what your looking to buy and im sure one will pop up that you like.
e39 5 series wagons are also pretty cool.
if you want an awd bmw, get an e30 325ix. i really wouldnt buy any other awd car for under 10 grand, its just the most awesome awd car ever.
as for audi, people will tell you to go with a b5 s4, but dont, its a great car to drive, but its going to have a new problem every week, and any m3 is a better car.
an old ur quattro would be sweet, but not great for reliablilty. there are some awesome 90's and coupe quattro's out there if you look. plus its way cooler than being like every other bro with a wrx.
you can pm me if you have any other questions..