I found that the biggest obstacle of DIY was just fear of the unknown. It just (at first) seemed like something that would be complicated. I mentally had it way up there with building my own mod. (Actually, even that has become demystified to me after this long....but I refuse to buy a soldering iron...

) Once I started DIYing, I saw the logic behind it all and it's so simple that I figured I was doing it wrong for a long time. BUT....I liked the juice and it gave me the nic I needed, so I figured what the heck. You can make it as complicated as you want....or as simple.
I premix my nic juice with some PG and some VG (more VG than PG) to the nic level I'm vaping at the moment in a plastic bottle used for catsup/mustard that I got for cheap at Walmart. I'm not sure how much it holds, but I mix about 240ml at a time. Then I bought a bunch of flavors I thought I would like from various places. I usually mix 10ml on the first batch of a flavor, and I use 10% flavor with 90% of my premix. I adjust the flavor while I'm vaping the 10ml bottle, then make 30 or 60ml of the juice if I like it, and I'm good to go. I have simple tastes and actually prefer one or two-flavor juices. I also NEVER vape tobacco flavored juices (which I'm sure would be way more complicated to make.)
I started buying in bulk almost immediately, and I can make 30ml of juice for around a dollar. I buy VG in 16oz. bottles, I buy PG by the gallon, and I get my nic juice 500ml at a time when it's on sale. I reuse my bottles, and the biggest expense turns out to be the flavoring. I'll never buy juice again, and haven't for over a year now. Actually, I got a whole bunch of those 39 cent samples back a few months ago from...??? (can't remember...they weren't very good) because I wanted the 6ml bottles to clean out and use. That was cheap for bottles....
I used a simple calculator at first, but now I just have my percentages down and I pretty much play it by ear. To me it's totally fun and easy and cheap. Could never justify buying juice ever again.
I used to get 2-3 packages every single week buying everything new I read about. Once I got my hardware down (REOs and HH 357s) the only things left to play with are drip tips and flavors.