On Saturday I dropped by Boing Online's "Headquarters" and purchased a large 5kg bag of fresh cut oaten hay for $12.
At first Rex wouldn't eat it, but after several minutes of sniffing and poking with his nose, he finally started to eat. Now he loves it! ^^
For such a small rabbit like Rex, the bag of hay is going to last for a few months.
Great value I'd say! =D