Early Modern cards have the potential to jet upwards out of nowhere (Necrogen Mists, for example). I think we could see a spike on Zo-Zu within a few months, IF, and ONLY IF, he dodges Commander 2015 reprint, which actually seems rather unlikely to me (that is, I think a reprint is too great a likelihood this year to go deep on non-foils). This threat of Commander reprint, combined with the upwards price trend (entering what seems to be a second bubble, which usually is accompanied by a change in slope of the baseline price) and Zo-Zu's ability to be a Commander himself, suggests that FOILS are the best route. The foil:nonfoil ratio for single-print foils that can also be Commanders can be staggerring (sometimes 10:1 or 15:1).
Buy foils around $10.00 and wait for it... Or grab non-foils at reasonable prices if you think it'll dodge a reprint. If there is no reprint, expect these guys around $4.00 by Spring 2016.