I thought it must be more than 10K...

Look at the basic expense for running a dealer.
1. Size: parking lot + showroom, 10 times bigger than any big restaurant. How much rent they need to pay per month?
2. Utility: Heat + electricity
3. Salary: Manager, Sales commissions.
4. How many cars a dealer can sell per day?

They must still have significant amount of room to make profit even below that "invoice price" in order to cover about expense.