I would focus on selling 5 things, kits, atomizers, tips, chargers and batteries. Pick the best of each and pull in some stock.
Juice is a hard sell, you can have a bazillion flavors but then you have to keep stock of every nic level and size plus the manufacturers may change the batches which leads to returns.
Just start with the basics, your RY4, 555, etc. and expand from there.
