Go online. Check enterprise or dollar online for one way. You only need one or two nights to drive down there.
Life is too short to let the ship of your dreams sail without you.
Carnival Destiny Feb. 2006
Carnival Fascination Feb. 2007
Royal Caribbean Grandeur of the Seas Feb. 2008 The DTW & MsBJ tour
Carnival Valor MsBJ and Dina Feb. 2009
Carnival Glory MsBJ and Dina Feb. 2010
Carnival Dream MsBJ and Dina Feb. 2011
mousesavers dot com (click on transportation)
both great sites for finding every sort of coupon code for a car rental. I go through most every code and combination and always end up saving at least 20-25%. Remember to sign up for whatever 'loyalty' program your rental company has as you can pre-fill much of your info and sometimes get a extra 5% off
AVIS do one way car rentals- I don't know where you are in Ohio, but I just put in CVG for Cincinnati Airport, returning the car to FLL for Ft Lauderdale Airport, and it shows rates starting at $120 day,in summer.
If you are a member of Costco or Sam's club, sometimes their discount codes will really make the difference when it comes to drop-off fees.
Also check the differences in prices for picking up from city locations versus airport locations.
Unfortunately with one way rentals, sometimes the rates can only be calculated directly on the company's websites. You should try with a few different rental codes if you can find them. Entertainment books have them, Costco, Sam's even unions and sometimes you insurance company as well. Collect a few online as well. You never know which of them might have negotiated a better rate when it comes to drop fees.
And don't get stuck on a specific size of car. Sometimes they need to move one size or another from point A to point B. And sometimes they don't even have the smallest economy cars. Dollar in Las Vegas used to always try to get us to upgrade from the economy to the compact... but we knew that they didn't even own a single economy car, they would have to upgrade us for free.