To many variables to give you the correct answer. I can give you an example of a purchase price of $100,000 , 3% down payment, 6.50% interest rate, property taxes of around $3000 year and paying mortgage insurance $41 month (required unless you put 20% down). This would get you close to $900 a month. It all depends on how much you would be putting down, interest rates and property taxes. Hope this helps you.
Lucy is exactly right. You should sit down with a good lender to help you navigate you financing options. The final purchase price will be determined largely by interest rate and down-payment. Once you have determined how much you can afford, a good realtor can get you options.
Email me if you need a lender referral for a pre-approval consult.