This is an interesting thread with lots of good information. I dabbled in diy one time and all my results were disasters lol. I'm thinking now that I may try again.
JD1 and tsbrewers, my first couple attempts weren't that great either. The great thing about DIY is if you screw it up, you can always add something to it or just pour it out and start over. It is so cheap, experimenting is not very costly at all. Make sure that after you mix it, shake it really good, then let it sit for at least 24 hours. Then, shake it some more and begin using it. If you don't let it sit, the individuals ingredients don't get blended so well, and you can end up with a mouthful of disaster. I mixed some cotton candy flavor when I first started, vaped it immediately after mixing, and it tasted like a dead skunk's ..... Now I have learned to let it sit, and it tastes more like cool, refreshing air with a hint of cotton candy sweetness.
If you buy in bulk (way larger than 60ml at a time) you get a much better set of numbers. I buy USP grade PG by the gallon for about $35, and USP grade VG for $2.50 for 6 ounces (180ml). I buy nic juice in bulk and on sale, too. The biggest expense of DIY for me is the $.65 plastic bottles and the flavoring. I can make 30ml of my favorite juice for about $3.00, too. Bulk is the secret...and sales. I order my flavoring directly from FlavourArt in Italy 120ml at a time. Waaaaay cheaper than any premixed stuff I've ever purchased from any vendor, even on sale.
BUT.....I have narrowed down my all-day vapes to a couple of flavors that I just love. If I were still searching for what I liked, I'd still be buying premixed.