are you in the US?
Aspire Nautilus X 4ML Replacement Kit
it's very easy to use, i have it on mine. If you do go for the nautilus X, trust me, use the 1.8 coil and no higher than the recommended wattage.
The 1.5 coil needs a chunk more power to get similar vapor, and it gives those dry hits i was talking about.
You could also try the 0.6 coil from the pockex kit , which will work fine in the X... basically you have 3 coil choices, the 0.6/1.5/1.8
the one i don't like the most is the 1.5 in this case.