Hi,
Florence did not charge me anything to receive the transcriptions of the birth records.
However, It took me years and several e-mails to them before they sent me that information, as they claim that they do not perform searches themselves. They have stopped responding to me though for any further requests.
The problem that you will find is that as you are looking for information pre-1808 - Civil registration only began in parts of Lucca from about 1808, and Florence only houses this information.
For pre-1808 you need to revert to parish records, and these are held in the church of the town themselves. You may find, as I have, that many priests are unresponsive to requests for information, even if you make a little donation.
You may hit lucky though.
Another piece of information that I have is the Stato di Famiglia of the family Mazzei from Pescaglia, which mentions 3 generations, but these were only common after about 1870. If you think some of your ancestors were still in Lucca in 1870, you can write to the Comune of the town you think that they may have come from in Lucca (ie - I wrote to the "Comune di Pescaglia" to ask for the Stato di Famiglia).
I have the arrival document of my Great-Great-Great Grandfather (Ferdinando Mazzei) from 1845, and he arrived at Dover from Ostend. This only states Italy as his origin though. As do all his UK census records.
The only way I found the town of origin of my family was that, luckily I found on the "National Archives" (UK) website that one of my ancestors (Andrew Mazzei) had a "Naturalization Record" from 1926. I received that, and found that he was born in Havre, France in 1887, so I then wrote there, and received his birth certificate that stated his father was born in Pescaglia, Lucca in 1852. I then wrote to Pescaglia for the Stato di Famiglia and found that the family originated from Stazzema.
Good luck in your research, and don't lose hope as it took me about 8 years to find the town of origin of my ancestors.
Regards,
Darin, Newcastle-upon-Tyne.