Get the FVPLR kit & get the booster. You will be able to fly roughly every 5000 feet & add 250 feet altitude. I can go out to 24000 feet with my stock P-4 with the antenna / booster kit. ( 17500 without it STOCK ) The Drone battery power is the limiting factor. With my P-4 FVP CUSTOM Drone battery mod I can get 33,000 feet. That's the very limit & scary but I did both above. The mods let me fly lower for the first 10,000 feet. Then I have to climb hard to keep the signal . All in all your looking at $250 for the Drone mod + batteries ( I'm working on the best battery combo ) Figure $120 for the batteries & the controller antenna & booster mod $390 But when done it's worth it. WOW 30,330 feet so far !!!!!!!!