I recently helped out at our school fete gardening stall and we were selling cheap copies of Jon Lamb's 'Grow Your Own SA'. It usually costs $14.95 from newsagents and is produced by The Advertiser. I have a copy of another of his books in this range on drought tolerant gardening and have found it really good.
Hope this helps. Sorry have tried to post the link but it wasn't active when I pasted it.