Hello Korvix, and welcome to the Forum! TheBlueAdept and KevN have done a nice job of answering your questions. I want to also add some links for your review that will be very helpful in learning your way around the Forum.
Click here for "New Member Links"
This link also helps when you're new and trying to decide which batteries will best fit your needs:
Click for "Food for Thought"
I actually like your idea of "fashioning" your own case. That's what many of us do. I use a case that came with an medicine injection kit. LOL It's great. It holds a lot of supplies and has 2 compartments. I know that eyeglass cases seem to be very well-suited for many members as well.
I don't want to overwhelm you with links...but I just thought of this link as well "When out and about...how do you carry your XL Batteries"
I'm not sure what the problem is with the Vapor4Life store site not showing both Auto and Manual battery options for the kits, but one of our Admin staff will be along at some point and may have some ideas about that. You are, of course, right. You don't have to start with a "kit", you just need to have the proper hardware and supplies to hit the ground with your feet running.
In the meantime, let me congratulate you on the switch from "analogs". It's a great accomplishment regardless of the amount you were use to using.