It depends where you live, your country in particular.
For example if you're in Germany you could pick up Lada Niva brand new for $10,000 dollars, that's less than 10,000 euros I guess. Russian cars are cheap to buy and maintain, but they do require a lot of babying -- on Russian roads that is. Lot's of gaskets you have to change, etc.
But basically you shouldn't go ahead and buy a car on your last money.
What is car, for newbies.
Any automobile has engine, transmission, suspension, brakes, noise insulation, interior.
An engine usually comes in variety of packages, it could be 4 cylinder, 6 cylinder, 8 cylinder, etc. The more cylinders an engine has the smoother it runs. Usually economy cars have a 4 cylinder engine, while business class cars have 8 and 12 cylinder engines. An engine has a crank shaft to which cylinders are attached, and intake and exhaust cams, which drive valves. Basically an engine, would either have a rubber belt connecting crank shaft with cams or a metal chain. If an engine has a rubber belt drive then it must be serviced every certain amount of miles. Also, engines could be interference, that's when if a rubber belt brakes valves and cylinders come in contact, and non interference. For best durability and less headache you should look for engines with metal chain drive and non interference valves.
Then there are power boosting technologies, which boost power on naturally aspirated (non supercharged and non turbocharged engines). One of such systems is BMW VANOS, which is a variable valve timing technology. (also called BMW ANUS) You need to research good into such systems, because many of them have quirks. For example, BMW VANOS eats a lot of oil, 1 liter of premium synthetic oil per 1000 km is normal for BMW motors.
Also, car motors are made of different materials, for example aluminum or steel. Steel motor blocks after service life could be rebuild, while aluminum motor blocks are usually throw away.
A car engine has a certain service life, measured in 100,000, 150,000, 200,000 miles, etc. Plus or mines thousands of miles depending how it was used, how often the oil was changed, and what type of quality oil was used. After the service life runs out, engine has to be rebuild.
Car transmissions can be automatic and manual. Manual transmissions are the most fun for a car guy, and from durability stand point are very friendly and reliable. Manual transmissions could be repaired if needed, and during car exploitation usually all you need is to change clutch every 100,000 km or so. Automatic transmissions can be of several types, they could be hydrolic drive and dual clutch. In any case, if an automatic transmission brakes, it is usually not rebuild-able. Also, cars with manual transmissions have better fuel economy.
Suspension is what makes an automobile comfortable, the more components the suspension has the more comfortable it is to drive that automobile. Another thing car manufacturers use in suspension design to make cars comfortable is aluminum. The less weight have the moving suspension parts the more comfortable car appears, and thus aluminum is used. Usually this can be seen on German luxury cars such as Audi, BMW. Problem with aluminum is that it brakes on bad roads and is expensive to replace. Thus car with aluminum suspension is expensive in service.
Any car has brakes. Brakes nowadays are usually of two types, all around disk, or front disk and rear drums on economy cars. The latter type has a certain addition service requirement, every few months or so you have to tighten the emergency brake, as the rear drums wear out. All brakes require service. You have to check every half a year or so the condition of brake pads and replace them in time. Also, every two years you have to change the brake fluid, and every month check that there is enough brake fluid.
Noise insulation is what makes the car quiet, usually cheap cars don't have noise insulation.
Finally the interior of your car are seats, instrument panel, and all kinds of controls.
Both BMW and Nissan are expensive in service. Especially the older vehicle you looking at for 10 or 20k euro.
Service cost
Any car has service cost associated with it. Service cost is measured per 100,000 km or (miles). It is all the repairs, all the tires, all the oil changes, and gas combined. The resulting number is euros (dollars, rubles) per km (or mile).
How to buy a car for newbies
If you are going to buy a used car, you basically have two choices.
A) From 1st owner.
B) From only God knows which owner.
Let's look at both cases.
A) You buying car from 1st owner. A brand new car has service intervals, usually every 10,000 km owner has to bring it to the dealer and perform service on vehicle. You need to ask the seller if he performed that service, and it would be very helpful if he could show you some documentation, like checks. What you need to watch out for are owners that say I didn't do anything to this car, just changed oil, it never once broke on me. Because any car has wear and tear associated with it, and although he did not have to do anything, you will have to service everything that he didn't service.
B) You buying car from 2nd, 3rd, or God knows which owner, they lost the count. Obviously this car has some serious miles on it, more than 100,000 km. You need to ask the seller what he has done to the car. Because a car guy would always do something to his car, while a penny pinching dude wouldn't do anything, even wouldn't change oil in time, and only fix things as they brake. If the guy says he hasn't done anything to it, and it never has broke on him, stay away from the car.
In both cases A) and B) you need to look at signs of car crashes, and if possible check carfax or something similar. Do not buy a car that has been in a car crash.
Also, in both cases look at tires. A car guy that looked for the car wouldn't have worn out all season tires.
Sit inside the car, close all windows, and smell the interior. If it smells like something and you can't really tell what it is, then don't buy that car. Because on crap car which didn't see service, people don't change interior filter and interior smells like something unknown and interesting --- that's the smell of a lemon guys.
