Anyone can share any info about LED lighting?
can we just change the normal fluorescent tube into LED tube or are they different?
was told to use 1 light costing $300 plus for each plant. is there a cheaper LED option?
The LED tube replacements can't use the ballasts. Each fixture will have to be updated to be compatible with LED lights. In short, you just bypass the ballast (I think you'll have to give the ballasts to a hazardous waste facility), but the wiring still had to be done correctly of course.
There are some LED lights that can use the ballast but it decreases the reliability of the light.
See http://www.designingwithleds.com/ for more info.