I here that bottom coil tanks really rock. I currently use carto/tanks with much success. What are the best bottom coil tanks out right now? Where can I get them? I have been hearing that Vivi Nova 2.5 is a great tank. Got Vapes (gotvapes.com) never had them in stock. I have checked every few days for about a month. Why would a vendor not put an estimated arrival date if it's going to be out if stock for more than a few days? Is there any other place to buy these?