Yeah, 80 gallons/hr for RO filtration is out of reach for most budgets. With that kind of output need, you'll probably just want to go with sediment and carbon filtration in canisters and forgo the RO membrane. This should give you the flow rate you're looking for. Reef supply stores are great for this.
The GE Merlin is 720 Gallons Per Day which equals out to 30 gallons per hour under optimal conditions. You probably won't get near that. It is priced at $390 at Amazon. As far as I know, it has the highest GPD output for the price.