I think that every time I see someone in here talking about a cheap 3rd party gimbal they're having problems with it working properly. I'm yet to see a "so I got this super cheap gimbal and it works great!" thread.
I also think you're slightly confused about Phantom2 models, here's quick breakdown:
The Phantom 2 Vision and Vision+ models come with a their own gimbal and camera which are basically not removable. You can't for example swap out the gimbal or camera... you're basically locked to that particular piece of hardware, and btw the FPV video is done via wifi so if you want long range you have to go modding stuff.
The Phantom 2 NON Vision usually comes bundled with a Zenmuse H3-3D gimbal (pretty much the standard, intended gimbal) on which you can mount a GoPro, or you can even get just the base P2 with no gimbal at all and add your own cheap / 3rd party gimbal. Adding long range, live FPV is really pretty easy especially if you have a H3-3D gimbal and gopro. There are plug and play cables and you just need a video transmitter, iOSD mini, and a few other things.
Ultimately the non-Vision, gopro route costs a few hundred more dollars, but it's a much more powerful platform. With the Vision you're locked into that hardware and you can't really upgrade the camera or use it for anything else like you can with a gopro.
Now that we already covered all that, be aware that there is a "gen 1 " Phantom 2 and now a newer "gen 2" or "ver 2.0" Phantom 2 with an improved RC, engines, and a few other things. My point being that the newer V2/gen2 made the price drop on the gen1 a little bit so they're slightly cheaper if you're looking to save a few bucks.
Also I see bundles on Ebay all the time
