if you are thinking about buying it, don't!

[navi tasan]

1) If you are thinking about buying an expensive car, don't.

I think that is a very common sentence. I was thinking about it and I thought that if I had to parse it grammatically, I'd say 'don't' means 'don't think about it'. But I feel that in reality 'don't' likely means 'don't buy it.

How should that sentence be parsed?
Could it parsed in two different ways?

This is a question about the grammar of the sentence. In real life, it all boils down to the same thing.

 

[emsr2d2]

You're right that technically it's ambiguous. However, it wouldn't really make sense to tell someone not to think about something when you've already clearly stated the possibility that they're already thinking about it.
The logical interpretation is that you're telling them not to buy that expensive car.