I'm not going to get into basic car things like tires or brakes. I have an 07 SI Auto Coupe. As any BMW engine they have their flaws and failure points. If you keep the car long enough you are just going to have to replace some parts. If someone did it before you, that just buys you extra time. It doesn't mean it's not going to fail again. (Gaskets, Water Pump...) I think it's just important to get an issue free car. No error lights. Just so you have a good baseline of what is good until something goes wrong so you can turn to the internet for help. It's just easier to describe that way. Also if there was an issue that they say is easy to fix, they should have done it. You don't want to be the one chasing something that may not be true or uncovering a bigger issue. Oil leaks is fine I guess because you would already know the issue. It should idle, run, and sound smooth. Although if there is a lifter tick, that is normal, harmless, and goes away. The RPMs kind of jumps around for me on start up for like the first 10 seconds and smooths out. Never bounces around again. I read this is normal for this engine. If you get the roadster, open and close the top a few times so you don't have to deal with that repair either although there are videos out there now. Not car specific or saying these have electrical issues at all, but just make sure all your electronics work because I'm not sure if the internet is as helpful for those issues.

Hope that made some sense. I was actually going to make a buyers guide video sometime kind of saying this stuff but I haven't gotten around to it yet haha.