The problem is that most condo's only allow their owners to rent once a year. It an owner rents just for a month then he has lost the opportunity to make money renting it out the rest of the year. Also you still have to go through getting approved by the board, a process that can have you waiting several weeks for an interview.
A home is a little easier to find because the owner doesnt have the same restrictions as in a condo. But usually a homeowner does not want to go through the hassle of a one month renter. The follow up cleaning and wear and tear, potential damage to personal property is just not worth one months revenue to them most of the time.