I was using the Nautilus tanks with an Istick for a month or two, then I got that "I need a little more" feeling. I then moved on to an Atlantis tank and Segelei 100W box. It was like night and day. The sub-ohm experience was just what I needed. Huge vapor, lots of flavor, I was in heaven. Coils for the Atlantis,then, were 2.50 to 3 bucks each! I use dark, sweet, coil killing juices. I felt I was spending too much on vaping, and worse, I still felt trapped by the need to buy the factory coils. They were just another thing to not run out of. I then started to research the rebuildables. I started with a Plume Veil dripper, as I was told it was a good base to learn building on. It was. Then I moved on to RTA's. I got a Lemo, then a Lemo drop. Moved on to A Cthulhu and finally have settled on a Billow V2 for now.
Point being I went through a lot of gear that I could have just skipped over. I wish I had just gone from the Nautilus right to the rebuilding. With regulated mods and this forum, rebuilding is safe and easy. Once the initial investment is made, vaping becomes nearly pennies a day.