For this information try http://www.ApartmentRatings.com or http://www.dataplace.org
There is a lot of information you can look up such as rental pricing reports and apartment vacancys in Southwest Florida
The apartment industry is not covered by real estate agents, but you can call several apartment complexes in the area and they may share their info with you. I used to work for Gables Residential years ago and I know it was required of our property to do a market analysis 1 time a month to make sure we were inline with the competition. If there is anything I can help you with feel free to call me at 239-289-1849 or log onto my site http://www.naplesrealestatepros.com.