If you also search Ebay for cheap emitters you may still be competitive in price for build your own. The attached photo shows one that I came up with. It was worth it when combined with the learning producing in bringing a PWB mill back to life. Don't imagine miracles, as Kleinstein says it is a square law problem, going both ways, so actually range is something like 1/R^4.
There are two huge advantages to a flood illuminator. One, it is often possible to place the flood downrange at locations of interest, eliminating one of the 1/R^2 factors. Second and vastly most important is that you will learn that these IR lights are quite visible to insects who fly around them as they do around visible lights. The insects attract spiders which build their webs near the floods. When the IR lights are co-located with the camera the reflections from the web strands capture the camera AGC and ruin visibility. Cleaning the webs is often needed on a weekly basis or even more often. So moving the light away from the camera eliminates the problem. If your system doesn't allow turning the built in lights off they can be masked off to stop them from attracting insects.