For your situation, I would go with an Arctic
tank and 0.2 or 0.5 ohm coils, paired with a regulated mod. There are a lot to choose from. The Arctic
tank can be had for under 20 bucks, which leaves you with a nice budget for a battery. I would look at the sigelei 75w tc, my friend got one for 50 bucks a few weeks ago, and then a 2 pack of samsung 25r batteries (10 bucks), and a nitecore d2 charger (15 bucks), and that leaves you with 5 bucks to spare if I did my math right.
Watch some youtube videos on subohm
tank comparisons, and look up mods made by companies like ipv and sigelei, or even the cheaper istick, and they will walk you through the various features and pros and cons so you'll know what's going on with them.