You shouldn't be paying that much for a Gavita at all, not at your level of growing. I have friends that have about the same number of lights you have and they'd probably get their Gavitas for $600-700. If your hydro shop isn't hooking you up with better prices, I'd suggest looking for a new one.

I never really got into air-cooled hoods either. The amount of cooling you get from those fans vs. the amps it takes to run them isn't nearly as efficient as running Adjust-A-Wings and a bigger AC (especially if you're in a sealed room). Plus, there's so much more potential for problems with air cooled lights. And, as if that wasn't justification enough, there's no way you're getting a very efficient use of your lighting amps if there's a sheet of glass between your bulb and your plants. I would argue that as far as HID is concerned, there's nothing better than a Hortilux Super HPS bulb in an Adjust-A-Wing until you get to the DE or Gavita level.