More good advice! It is a mixed bag if you read through the forums, there are some who have dumped their car because the car was giving them fits (not super high miles I believe) and then others who are fine. That is always the problem with a used car, it is sometimes a crapshoot.
Can you have the car inspected at a BMW dealer? I would ask that they pull data from the system, things like number of launches using the launch control, redining, etc. It does have a record of this. If the car was beat on you might have cause for concern.
If it is SMG see if it has been replaced. It seems to go around 35k to 40k miles. It is rather expensive to repair or replace. Here is a link to another thread regarding the subject, if you look back over the last couple of months you will see several threads just like it.
Well, I guess it's my turn...
My 650 shares many interior parts and electronics with the M6, so there are issues that carry over. I have an extended CPO warranty from BMW, I have had around $4500 in covered repairs in the last 3 years. My instrument cluster crapped out, my dynamic drive ARS block died, my steering angle sensor failed, lastly my tranny had a sleeve that leaked (wouldn't correlate to the M since you don't have auto-tranny). I bought the car with 27,000 miles and currently have 50,000.