Need advice for purchase 😛

Hello together, I want to buy a used SLK next year or later. Is just my dream car. However, I have some questions. I have about 20,000 available… Do you get something decent for it? Have seen from various providers on the Internet that the used ones start at about 22,000… and have run from 40,000. What should you look at with this car? What weaknesses are there? How old should it be at the most? And at what number of kilometers catch And what else can you tell me about this car in general? I really have no idea about cars … I’m just a woman.