OK.
They are selling you a system at $7.50/watt. (that's about $2 more per watt than we install for on average, after we deduct labor)
They are telling you that you will qualify for the $4/watt Florida rebate which will be $9200.

And they are telling you that you will get Fed tax credit of 30% of the SELLING PRICE.

IF you take the 30% tax credit off the Selling Price, you will have to claim the Florida rebate as income.
Otherwise, deduct the Florida rebate from the Selling price and take the 30% Fed Tax Credit off the balance, which would be $2415 Tax Credit with a cost balance of ...$5635.
What suprises me is that they didn't deduct your energy savings and Renewable Tax Credits that would be produced each year off of that, to give you an estimated payoff timeline.

Now as far as the Florida Rebate goes, have you checked into it at all? Is the PV company willing to take over the rebate, and how long will it take to get the rebate?
Check out this website from Florida's rebate program to see if there is even any money availible:
http://myfloridaclimate.com/climate..._energy_initiatives/solar_rebate_program

even the dsire website states there is no more funding availible. So, if and when it ever is availible, you will most likely be put in que, but the question is, how many years will it take to get it? I would not rely on getting it to estimate a payoff on this system

As far as the Canadian Solar Modules, they are pretty good. Not as good as some, but better than others. They also have different module lines, so some have better specs than others, but I believe they all have a +5w power tolerance rating, which is good.
A company called Ready Solar (which is 'solar in a box') uses Canadian Solar Modules with enphase inverters. They aren't a 'cadillac', but they aren't low end junk either.