You apparently have almost no preference in what you want, so that works in your favor. That said, here are a few schools of thought when it comes to buying a cheap used car.
1- When in doubt, go Japanese. A lot of people buy into this theory, hence used Hondas and Toyotas fetching higher prices these days. It's hard to go wrong with a Honda 4 cylinder, but there are still things to look out for (for example, early 2000s Honda automatics were notoriously weak links).
2- While avoiding known problem cars, buy the newest car you can afford. Self explanatory. Newer is good.
3- Generally speaking, ignore make and model and just buy what seems decent. Search around and look for cars that genuinely seem like good deals. Well kept cars in good shape with decent mileage and fair asking prices. It's always good to keep your mind open in this regard- if you're only looking for a specific car or two, you're missing out on a lot of potential good cars just by not looking at them.
4- **** it, buy something fun. This doesn't really apply to you because you seemingly don't know what you want. But if I was looking for a cheap used car, I would say **** it and buy something fun. It's a cheap used car... in the end, they're all kind of a crap shoot so I'd buy something I like rather than something practical. 8K to spend? I'd look for something with a V8 and cross my fingers that it holds up.
My recommendation:
2000-2003 Nissan Maxima
Local Example:
Nissan : Maxima | eBay
Not so local example:
Nissan : Maxima | eBay
Legitimately nice cars with fantastic, well regarded engines. Back when my old man was working, his company had 3 late 90s Maximas as company cars. Every one of them went over 200k with regular maintenance. The Nissan VQ V6s are very good.
That said, I believe most in option #3 that I listed above. You're not going to spend a lot of money so it's really no time to be picky. Keep your options open while you're out there shopping. Using Consumer Reports annual auto issue as a reference (not a bible, just a reference point), find out which models to generally stay away from and just go out and find something decent.