You are correct about there not being a standard size at MCO so you can pick from the full size.
What ID and/or coupons did you use to get that rate? I am getting $179 before taxes for 9/15-9/22 using my insider ID.
They do not have a standard area at MCO for Alamo/National, however, they do have standard cars, they just mix them with the full size cars. If you book a standard size car, you will be directed to the full size area.