I buy bulk 1.5 ohm coils from dhgate, no they are not "Kangertech" authentic bla bla blah. So far they last every bit as long as "authentic" coils. The only difference I have noticed is that the ohm range fluctuates more between coils of a said ohm. Mostly 1.6 ohm. I did get a 1.4 and I fricken LOVED IT! immediately bought a 3.1es so a can get lower.
Less than a buck a piece shipped and I just ptch em when the hits taper off and don't look back.
Wow a month?!!!!! never done better than a week with any coil, mostly two to five days and mostly three like clockwork.
Do you mind sharing were you get these?