The cheapest car I ever bought was a 1977 Malibu for $300 that I drove through high school without putting a single repair into it, albeit I did have to dump in a quart of oil every other fill-up. On the plus side, though, I never had to get an oil change, so it kind of saved me money, actually.
The best car I ever bought was my 2017 BMW 325ix.
The car that best balanced cheap and best I ever bought was my 1988 Volkwagen Rabbit Wolfsburg. I bought it for $1,600 with 84,000 miles. I drove it all the way through college and delivered 10 bajillion pizzas in it. I called him Sherman, because my friends said he was deceptively sturdy and tough like a little Sherman tank.
Tied with that one would be my 1999 Subaru Forester I got after college. I bought it for $6,000 and it only had about 70,000 miles on it. My sister is in college and is driving it still. Her name--the car, not my sister--is Subi, and she is invincible. I think she presently has 350,000 miles and is still going strong.