No. Not a good starting point for financing anything. That is a dealer catch. You can get items within your monthly budget that are over priced and over valued.
There are a number of free mortgage planners out there that can assist you in knowing what your max loan value is and help you fit it into your monthly budget but the dealer does not care about that.
Figure out your loan ceiling and then stay within that when negotiating. Look for the best value within your budget.