The cost of getting to AKL as an addition to a DONE3 depends a lot where you decide to stop and add the connection as a separate ticket. SIN/HKG/NRT (although I didn't price them) would likely no be high on my list. CMB and SGN however, might offer a great deal more savings. And even though further from AKL, would offer less expensive tickets. And in the end a return ticket will (err) return you to where you paused the DONE3.

OTOH, had you said PER rather than AKL, SIN would be the logical stopping point.

Be creative in your wandering

Fred