I have never heard anyone describe "Autodesk" as "cheap software"
However the "Sell software cheap and then charge for service" is the OPEN SOURCE MODEL, where the software is given FREELY, and if you need professional help you have to pay, that is certainly not the model Autodesk uses.
Cheap compared to the service contract. If you sign up for things like paid training they'll basically give you the licenses for free. This is from experience, at least for new companies where they want to get lock-in.
I don't see how it being the open source model is relevant. I'm not judging the validity of the practice, this is literally what the representatives claimed the logic was.
