A couple things I'm looking at right now or for the future:
DCtanks in colors/clear 3.5/5ml without the DC cartomizer the
smok Tech ones I see them on a site selling just the
tanks in clear for about $5 (plastic caps) and colors (chrome caps) for around $8..I'm probably going to buy 4 or more of these in the near future.
SD Keyring or the long auto 510 batteries (280mAh ones)
Replacement CE2 style wick (if you could get the wick material I'm sure there are a few people around these forums that would buy it) for rebuilding and making atomizers ect.. and maybe the wire for
coils (I have a ton of nichrome wire for now though)
Replacement metal CE2's in the future (I use the 2.5ohm ones).
Well just a couple things I can think of for now and if I think of more things I'll edit or post again
Edit: You might want to checkout the variable voltage "vision tox" in the future as it looks like it might be the next good tube vv mod..I was looking at them before buying your VV mod but right now they have a couple issues it appears..6 months down the road if the "tox" is ironed out I might be in the market for one..they have a better readout (OLED) then the "LT" style vv mod.
510 battery to eGo (with the eGo outside thread) adapters might be good to stock a few..if you had them I would have bought one to use my DCTank cone on.