Hi, I started with NJoy's NPro for the same reason you did. It was one of the only e-cigs that I could find at my local smoke shop. It was WAY over priced for what I got. 1 auto-batt, 2 cartos, a usb charger and auto adapter for $50 + tx.
The battery life was short and after a couple of weeks I had to draw really hard to get the batt to turn on. I bought two auto batts from NJoy. The new batteries had better draw but took over 2hr to charge and lasted less than one hour of hard vaping. I email them twice about the discrepancies and got no reply.
To answer your earlier question: Yes you can refill NJoy Cartos. I have been refilling Cartos from NJoy with e-juice and they work but get a burnt taste after a few refills. There is no way to clean them. I would guest-a-mate that their 5 pack bottle ($19.99 on NJoys website) hold about as much juice as a pack to a pack and a half analog cigs. In no way a savings. Also when you read NJoys warranty it states:
During the warranty period, NJOY will, at its discretion, repair or replace (with a new or reconditioned unit) components that are defective.
The NJOY product (cartridge, battery, or charger) is not designed to be refilled or modified in any way. If any foreign substance or liquid is added to the NJOY vaporizer or cartridge, the warranty is VOIDED.
Look around. Check out prices and warranties. I just purchased a P510 kit from Vapormaxx and am loving it. They responded to my calls and emails quickly. Their prices are competitive and their warranty states:
Unlike other E-Cigarette brands, Vapor-Maxx products come with the only life time warranty in the industry.
And remember, all hardware is warranted for life, if you have any questions or problems with the operation or function of your new Vaporizer feel free to call or email us. We are here to help you in any way possible to free you from the offensive and deadly grip of Tobacco addiction.
Hope it helps
Malt