Regarding the LED strips, I have a price list from one China company (SE-LED.com) that sells 5050 sized RGBW strips. They are 60LEDS/m, 17W/m. Works out to around $7.50/m (CAD currency). Part number is SELS-5050RGBNW30-12 if you're looking.
If we space them every 6", that's <40m which would cost $300. 15% cheaper if we don't want silicone coating to waterproof it, but I'd think we want that.
I'm not married to this company so feel free to find cheaper or different strips.
Scott, I've dug up our Facebook thread and copied it below in case you wanted to reference:
Back of napkin here, because I'm totally guessing at most of the numbers, but... those halogens are probably about 350W because we trip breakers if we add anything else, but can run them continually on a single 15A. (So they're probably not 500W.) A typical 350W halogen is around 5000 Lumens. The arena is 6 feet by 8ft? If all of the light from those four halogens is landing in the 4.5M^2 of arena, we have a light level of around 4500lux. That's pretty bright, and I doubt we are actually that high, but I guess that would be a design target for any replacement lights. (Well, since the M^2 doesn't change, we can just aim for 20,000 lumens total.)