Before you even start..
You're going to have a lot of competition in the vape field. Everyone and their mom's doing it, added to that there are online sources that buy in bulk and will beat your prices easily.
Those coils are only for a specific type of tank (Kangertech), not universal, so your buyer base is going to be limited to Kangertech users.
If you want to make sales you're going to need more than one product for sale, always the latest product too, and competitive prices (goodbye profit margin), generally sales are better with universal products like mods and RDA's.
I've always felt like tanks and specific tank coils were a China scam to get money from noobs too lazy to buy a roll of kanthal and learn to twist a coil.
Buyers are starting to mature also, they're realizing there is no need to have 10 different vapes that all essentially do the same thing.
With that said..
eBay and Craigslist in bulk lots is your best bet.