You make your own decisions obviously but I suggest 0mg nicotine ejuice if you've no addiction to it. On top of that you'll want at least 60/40 or 70/30 vg/pg ejuice for good clouds. Max VG ejuice ratio depends on the manufacturer.
The absolute cheapest easy thing to produce some clouds is the Joyetech Penguin. You can get it for $12 off eightvape.
The best box mod starter kit with an internal battery that won't break the bank is probably the Innokin Kroma-A or the Vaporesso Tarot Mini. The mini should have a better atomizer for getting some good clouds but it has 2ml limit for liquid and caps at 22mm for tank size.. The Innokin has a very average atomizer but we're talking about 4ml liquid and 24mm tank.
As for a box mod that won't break the bank and has replaceable batteries, there are a few that are really good, but it's hard to recommend anything over the Eleaf iStick Pico 25 if you want the best mod of that type. Now if aesthetically speaking you wanted something sexier looking and very functional the Vaporesso Tarot Mini fits the bill. Less than a week the Vaporesso Swag mod kit comes out as well, and I don't personally doubt it'll be a good mod.
Smoking mods are usually visually appealing but I've heard too many horror stories. Kanger mods look great and were one time very functional but quality control seems to have gone down a bit and even if it didn't their mods are basic in comparison to more recent offerings. Innokin Coolfire mods are nice for internal battery, but I fail to trust the Coolfire Ultra as the logistics behind a 4000mah internal battery running a 150w confuse me and I'd bet that battery is shit and the whole device performs like shit.
Stores for cheapest prices are breazy, eightvape, and misthub. There are coupon codes in the reddit sidebar under recommended suppliers.
Internal battery mods will eventually die forever, you can't replace the battery. External battery mods I've listed require 1 18650 battery. Use a trusted supplier for batteries, do not buy them off amazon or ebay, if you buy a fake that's on you. You would also buy wraps for your battery there is information on the sidebar to assist. Use Mooch's graph to choose your battery type. Prime your coils.