Can ( and would you want to) you live in the building also? How would it compare to rent?
You say expense is $1,500 a month. Does that include your mortgage? Probably not. How much would the mortgage cost each month? What about taxes, insurance, and any other fees you have to factor in?
Figuring your monthly payment include the whole purchase amount. You may not be paying it, but that is really how you determine if you are in positive or negative cash flow.
I would not want to use all my money in a down payment. If you keep some back you would be prepared to buy any repairs that come up.