If you have owned your vehicle less that 6 months, AND you state charges less than 6% sales tax, you will pay the difference to the state of Florida (MD charges 6% so we paid nothing).
As I stated, we had NO problems becoming residents of Florida. Getting our driver's licenses took 30 minutes for the two of us and most of that was waiting in line and waiting for the picture. We did have bank account info and investment account info and car registration and car insurance all at the same address - the Good Sam Mail Service.
We also registered to vote while at the DMV. We got a nice letter from Okaloosa County (where Crestview is) explaining that, because we have a postal box but not a dwelling, we must vote at the courthouse. They didn't seem to mind at all...
The initial vehicle registration fee was $225 for each vehicle, plus $28 for the tag plus $45 for one year registration.