Ok... here's the deal, wireless cams from ebay generally get 10m distance(I would say most, but they can be modified). Sometimes more but not much, you can increase the distance by changing antenna on the receiver(little greyish white box), or tuning the tx itself etc. Pretty much pita plus u would need some other equipment to get her to work right. I would suggest looking at rangevideo.com, or nghobbies.com i think it is etc. There are a couple other outfits that specialize in long distance stable wireless systems(for rc airplanes), a little more money but worth it. Yet another issue... maybe maybe not is frequency, if you get 2.4ghz and run 2.4 ghz then it not work very well(if you have spektrum, turn on video system first then radio, but even then it still affects video).
China systems aren't technically legal, they run around 2.1ghz or something like that... ummmm... then u would need to bring tv, and a recorder of some type. Oh and quality, no where near an on board system.
Other option is to get camera, I've had good experience with panasonics for the planes, handle vibration well and colors are exceptional. Ummm had a canon sd something and it was ok, did not shoot very well with vibrations. A lot of the guys are dipping into cheap asian made video cameras that are doing HD 1280, these turn out good videos. Problems with some is the format they record in are generally apples, which for any one without mac is pita to edit or at minimum convert to other format. Ummm... other downside of real camera, keeping it dry, plus it'll be bulkier than wireless sytem, unless of course u stripe camera down to board and lens, run power off esc etc.
Anyways if you want to know more about both, highly suggest u do some reading at
http://www.rcgroups.com/video-piloting-fpv-rpv-469/
Ivan.