Very happy here with my istick and nautilus mini setup. Very affordable and very lightweight, battery lasts a long time, great flavor and vapor with low power consumption. No issues yet, been a couple weeks, same coil. I will avoid using high VG eliquids and liquids with sweetener, to try to stretch the coil life.
I got my istick from vapenw.com. No problems and it shipped out the next business day. For eliquids, read the eliquid forum and see what sounds best for you. 50/50 vg/pg is good for me with the nautilus mini. I like to spend a little more money for good eliquid. For cheap eliquid, I have been generally pleased with mtbakervapes 50/50 mixes for my eliquid although I prefer Nicoticket's product, it's just more pricey. For the nautilus mini, I think Nicoticket's Betelguese eliquid would be a good choice, for a fruit flavor.