What is an average price of a house that a young couple 19 to 20 could afford?

Call a local bank and ask to be prequalified for a loan. They will compare your income, bills,etc and run credit if you allow them to and tell you where you stand and the maximum you can borrow. You are not committed to borrowing from them but it will get you started and tell you what price range you can look in, how much you neeed to save, etc. Then ask yourself if you two feel that is reasonable. Can you actually make that monthly payment comfortably? You don't have to borrrow the max they will lend you.