I spent some time out this morning trying various configs and just getting to know the flight dynamics of the frame/quad that I built. It's the standard 3DR X form quad, with sonar mounts front and back. I also added some foam to the landing gear to see what type of 'landings' it could withstand. Aside from the collet crash (which broke a landing gear) it handed everything quite well. However, mounting anything heavier than the sonar, telemetry or RX [ie, my GoPro Hero 2] is a no go on the mounts as it just throws the balance off too much.
Video here: https://vimeo.com/54703121
The first link you posted is the one I bought. Not assembled as I wanted to know what I as getting, how to build it as that would then help with trouble shooting and well, replacing broken parts. If you are looking at getting it, make sure you get the ublox GPS and not the mediatek version.
I bought a sonar, multiple sonar mounts (they're useful for mounting other things), telemetry kit and numerous spare parts (additional props, landing gear etc). I also bought upgraded collets and prop adapters, some loctite (and nail polish believe it or not to keep things sticking when I didn't want to loctite the hell out of something) and some foam balls to act as landing gear protection.
You'll also need to get a radio and battery. I bought the spektrum dx8, which came with an AR8000 [and two others] receiver and a 4000mah 4s battery. I actually just bought a lipo battery alarm and tester. The alarm will be attached to the drone when flying so I don't have to worry about how much power i have left. Link here - http://www.buildyourowndrone.co.uk/LiPo-Battery-Alarm-p/lipo-alarm.htm
The tester is so I now how much power is left in a battery if i'm out in the field and don't have my charger with me. Link here - http://www.buildyourowndrone.co.uk/LiPo-Battery-Tester-p/lipo-test.htm