In reply to ams558: if you can't find them in the UK, the cafe in Natimuk (the closest town to Mt Arapiles) stocks them. (I'm assuming you want a guidebook because you're going to visit)
There's also a newer competing guide that's just been released, something like "Arapiles: 444 of the best". With 444 routes it's even more select, but will be cheaper than the other guidebook.