Wholesale price is only the beginning. Look at the full cost of owning that inventory:

• DOA rate: How many units arrive dead on arrival? If it's more than 1-2%, that eats your margin. Ask the supplier for their typical DOA rate and their replacement policy.
• Charge time: A device that takes 3 hours to charge is a pain for customers who want it ready now. If you're selling to people who are always on the go, that's a factor.
• Returns: What's your return policy? If a customer gets a defective unit, will the supplier replace it, or are you eating the cost?
• Shelf life: Disposables have a shelf life. A device that sits for 6 months might lose flavor or battery performance. How fast does your inventory turn?

For example, a VERTEX-VISTA might have a larger battery and higher price, but if your customers are used to a smaller, cheaper device, you'll have to discount it. That discount eats your margin.

Look at the Vape Cost Calculator to run the numbers on different devices and see which gives you the best return after all costs.