SeasonalRentals.com is a great place to search for seasonal rental properties by Realtors.

I have a two bed, two bath, manufactured home, 177 Lake Tarpon Dr., associated with an over 55 village on Lake Tarpon, has large heated pool, club house, golf, shuffleboard, other activities,
basic furnishings included, cable and phone not connected, $700 month. Cliff acsully1@hotmail.com, 727-366-8240

I do know someone who deals in rentals in Dunedin--give me a call and I can get you the info! 727-452-0023

Anne,
This forum is primarily used for exchanging information about buying and selling property, not renting it. Therefore, I direct you to google (I think you'll have better results there): the google homepage is attached as a blue hyperlink below (in the line which says "Web Reference"). Click the link and type these exact words:

Dunedin FL seasonal rental

into the search box. Hit "Google Search" and presto... You now have tons of stuff to check out! Enjoy your visit with us down here in the "Sunshine State"... Best of luck and happy hunting!