One thought I had about this was camera suitability. If you place the cams 25 feet away from your target, even with a narrow field of view, most cams that we use might make the target appear "too small". I suspect that the targetcam system you mentioned has some sort of zoom lens. Not sure, but it's something else you should check into. (Buy one cam and test it out to make sure it meets your needs.)

Here is an example of an adjustable zoom cam: http://www.ebay.com/itm/Mini-1000TVL-CMO...1655001961
(There are even cheaper ones on eBay - but something to consider.)

You need a proper receiver, I recommend immersionRC or Banggood "Realacc" receivers, they have awesome picture, much better than any other receiver I tried. (On 5.8 GHz) I recommend helical antennas on both sides, you should get away with a 200mW tx. For camera, I recommend the hs1177. You can buy one for about 30 USD, its quality is amazing. As for the monitor, just buy a generic 7 or 10 inch one. I recommend a 5000mAh 3S battery for both (and 3A mimi step-down regulators on both sides, they are very good)

http://www.ebay.com/itm/Mini-3A-DC-DC-Co...xy5QtSA2eR