"But good quality
led's are not cheep, and only have an effective distance of about 18 inches"
I can pop 2,000 umol (sunlight intensity) near 10 inches. The low range of high light levels begins around 150 umol. With umol count halving with each doubling of the distance, 250 umol is therefore 80 inches away.
Bear in mind most
fluorescent lamps don't even hit that output from 24 inches, that includes T5 and Induction. A 200w Induction lamp won't even hit 2,000 umol from the surface of the tube itself.
I have a 12w spotlight with lensing, 2,000 umol is 20+ inches away.