You can buy roughly 4-5 years of reflectors and bulbs, excluding the ones included initially, for the price difference alone. Before those 6 years passed and certainly long before those 10 years above passed, there will be professional led lamps that will make both the gavita and the current led (especially diy white cob leds) a bad choice.
Besides that, the gavita pays back for itself and more. If you can't afford that bulb and reflector after a year you shouldn't be growing with professional horticulture lighting. Same for not being able to grow quality under hps... in that case something like led or T5 may be a better choice, easier to manage perhaps.
Being able to replace the reflector part of a gavita fixture separately isn't a downside.
The lifetime estimates of LED assume a professional application. People replace cobs and drivers too.
Can't argue with the disposal point. Those cobs are much easier to trash.
If money matters so much, you want to get as many as possible quality dense nuggets from tall colas on a given space. For that, gavita beats all. If you got plenty of space extra and want to compete in an imaginary efficiency race, DIY LED beats HPS.
High ppf + higher than by led fans recommended temps = max cannabis production. According to actual scientific research anyway...