Property taxes in all of Monroe County (Key Largo, Islamorada, Marathon, etc.) are approximately 1% ,or a bit less, of the purchase price. We have the lowest property taxes in Florida. Great reason to buy here!
You can usually find them on the county tax assessor's web site. The taxes are often different, even when you're looking in one city. If you don't know the county, you can probably find it on the U.S. post office web site at http://www.usps.com. Sorry. That's all I have at the moment.
I live in Islamorada. This is Paradise! The taxes for '07 were .92. As in all of Florida, we have Save our Homes. If you homestead your property, your assesed value cannot be increased more than 3% per year. They can change the millage, but cannot increase the taxable value.