I still have no troubles buying the coils for my subtank.i mainly use the claptons.
Similar vape is the eleaf Melo 2 (another old tank ) takes eleaf ec coils and Atlantis Evo coils still has the best top fill system I've used. Melo 3 is also good, takes the same coils as well and easier to find these days but the top fill isn't as good
Also the kanger pro tank 4 , takes the same coils as subtank with a top fill similar to the Melo 2.
Not the best for flavour by any means but for good reliable , leak free tanks that don't drain juice like it's going out of fashion can't go wrong with any of the above
Like has been said though for any of them you'll be ordering from China these days