I want to make Chaos Goliath.

So, I really want to play Chaos Goliath. I haven’t played yet, so at this point I’m just going to wait for the new game to come out and buy the core set. However, I will also need the book of ruin. If I can find one for a good price, should I buy it now, or should I wait and see if they reprint it for the new release?