To pay or not to pay up front
To put it in perspective most flying schools are businesses and the primary point of starting a business is to make money - the service the business provides is usually secondary as most businesses have to report to shareholder(s) who want a return on their investment.
To most businesses cashflow is vital and therefore they like cash upfront because it allows them to plan their business, forecast for the future and pay their overheads - the largest of these (usually) are salaries.
Flying Schools offer pre pay packages to get the money in: for the student there can be many advantages in taking up one of these packages, principally it will be cheaper.
However, there can be disadvantages too, for example if you are not happy with the service you are getting, or you want to go somewhere else (etc), you are in a weak position as they have your money and you will find it difficult to get your cash back.
Obviously if the school goes bust then you will probably never see any of it again - this clearly would not be the case if you paid by the hour.
So you have a choice - either you want to save money or you want the flexibility to be able to go somewhere else if you're not satisfied. (And this goes for all flying schools, not just those in Florida).
Personally, I have a JAA ME CPL and an FAA ME/I. I have been to fly in Florida several times, however not with OBA (yet). I have both paid up front for courses and also paid per hour.
You must make your decision based on your financial circumstances and your desire for flexibility, having read all the advice on here. However be aware that there will be many unforseen extras that crop up and flying usually costs more than you expect - for many reasons. So if you decide to pay up front make sure you have access to extra cash to cover any possibility!!!