was thinking of buying a used briefcase to transport my 8 tanks, 16 bottles of juice, and a few mods.
The following isn't "cool", but it would certainly provide a safe method of transporting everything. It would also be a
whole lot less $$!
Unless your tanks are really tall...each 1 will be protected and fit nicely down inside an empty Rx plastic pill bottle w/cap, that you get from the pharmacy. That's how I carry several on vacation with me. You could most likely fit a vape band around each tank, too, if you didn't want it moving much in the pill bottle.
Your bottles of eliquids and your mods can be protected, separately, in rolled down fairly thick socks (to form sort of a nest in the center). If you want better protection for the bottles, and they're not huge around....buy a cheap styrafoam swim "noodle", and cut it in lengths that each bottle will fit down into.
The really inexpensive, very sturdy, black canvas, small tool bag at Harbor Freight (approx. $4.99 w/a coupon) would hold everything with no problem. It has very sturdy handles, too. IIRC, there's even a couple mesh pockets inside it that could hold the pill bottles with your tanks in them, in an upright position.
ETA: Those Apache cases, and others that are similar, are great if you're transporting really expensive camera gear, or pistols, or very sensitive electronics gear. But, for several tanks, bottles of eliquid, and mods...IMO they're way overkill and expensive... for just moving across the country, especially if you're going to have the case or bag with you, and not amongst everything else stacked in a packed moving truck. Spend the $$ you save by not buying 1...on another tank, or eliquid, or mod, when you get there!