You can get the Justfog Q16 starter kit at a reasonable price now! Its battery capacity is 900mAh. The voltage can be adjusted from 3, 4 V to 4, 8 V. With a J-Easy 9 battery you can adjust the voltage in 8 easy steps.
https://www.rookwinkel.nl/elektrische-sigaretten/justfog-q16-starter-kit.html