The best tip when going to look for a car is to take someone who knows what he's doing with you.
You could put down a list of cars that are in your price range in Estonia so people here could suggest viable options.
I looked through the ads and for about 600 to 1000 Euros the list is like this...
http://www.auto24.ee/kasutatud ... =0&ag=1&otsi=otsi
Basically the most common cars are early 90s Audis (80, 100) and BMWs; mid 90's Escorts, Mondeos and Scorpios (but they're butt ugly); Sierras; early and mid 90s Civics; some older Kias and Hyundais; Mazda 323 and 626; late 80's, early 90's Mercedes-Benz; older Mitsubishi Colts, Lancers and Galants; mid 90's Nissan Primeras, Almeras and Sunnys; mid 90s Opel Astras, Vectras, Omegas; mid 90's 306s; Ladas
; Golf mk 2 and 3; early 90's Passat; early 90's Volvos. There are other cars but they're more rare and thus should be more expensive but if it's rare and cheap then it's most likely a heap of junk.
Good luck.