The short answer
At 250 units most US property management software costs $250 to $550 per month before one time fees. Yardi Breeze, Rent Manager Basic and Propertyware Basic land at about $250, DoorLoop Pro lists $344 billed yearly, AppFolio Core is reported near $373, Rentvine is quoted at $375 or more, and Buildium's plan floor plus one online rent payment per unit puts it near $530 to $550.
Letting costs $224 per month at 250 units billed yearly, the lowest subscription in that list, and it does not go up as you grow toward 500. Month to month it is $449, which is more than the $1 per unit plans and DoorLoop. Letting does not collect rent, screen tenants or list vacancies: tenants keep paying into your bank account and Letting reads the bank export.