Following a recent discussion on shed lighting I thought I would check out what was going on gumtree and found a very cheap source of fluoro lights.
Double Fluorescents Weatherproof $10ea/$500pellet | Outdoor Lighting | Gumtree Australia Stirling Area - Osborne Park | 1110874622

The lights were temporary lighting used during the construction of Fiona Stanley hospital.
The fitting is a cheap chinese type but they are weather proof and more than adequate for a shed.
Some have cracked covers, paint dribbles and missing cover clips but you can hunt through and find the good ones as there are many hundreds of them to choose from.
Mine had Phillips tubes and a short power cable with 3 pin plug but the earth pin is round so will need a new plug.
I used old computer power cables (kettle cords) to rewired mine.

They cost $10 each, they also have singles with battery backup for the same price.