By Veronika Bondarenko Realtor.com found cities where some are putting down 30% down payments and others where one will only need 4%. For those trying to squirrel away enough for a down payment while also paying rent, 25% instead of 15% can also mean the difference between locking in a mortgage or watching prices rise for another few years. That is why many looking to own are increasingly moving away from the old 20% standard suggested by financial advisers and locking in a mortgage as soon as they have enough to start that conversation with an agent — a report from the National Association o…