When you rent the amount you pay per month is already determined and advertised. Your bad credit might mean they won't rent to you but often if you avoid apartment complexes and rent directly from an owner they will overlook or not even pull your credit.
When you buy the amount you pay is actually a factor of your credit score. Bad credit? You'll pay a higher interest rate. I'd work on fixing your credit score and personal finances so that you no longer are a credit risk. Then go searching for a home.