Thrifty does one-way rentals. Check their web site for availability on the dates you need and the exact Florida city which is your destination. Use the Orlando Magicard corporate # 004M001010 to get good rates. You may print out your Orlando Magicard here: http://www.orlandoinfo.com/magicard
Back in November you can get some really good rates (the rental companies were moving cars south for the winter), but I do not think they are still available
Unless there is a special where they are intentionally moving cars South for holiday travel (winter), $180 is not out of line for a one way drop charge.