???'s about fluorescent tubes for small room

i've got a small area to grow in that is 4 feet wide and 2 feet in depth and about 8 feet high that will be split into two levels but i would like to use fluorescent tubes for the vegetative stage but i can't figure out how many i should use i wanted to use 36" tubes but i'm unsure how many i would need and of what watt because i've noticed the wattages tend to be very low. or where i can even find them?

The big box lumber will have them. You might need to look for 4 footers. Or 2 footers.
160w fluorescent grow under $100 total. - Marijuana Growing

This fellow grew his all the way to harvest with 4 tubes.