One of the things that put me off doing DIY is that all the material I've read on it suggests that it takes a lot of time and patience. You make a tiny batch and put it aside for a couple weeks while it steeps. Over the next couple weeks, while you're watching the first batch slowly change color, you make several more tiny batches. As each batch reaches maturity, you might need to make notes on adjusting the flavors and ratios to get it where you like it. Some are just awful and require either more steeping or a trip down the drain. Also, pg and vg are cheap when you buy them in bulk, which will save tons of money on juice in the long run, but your initial investment will be substantial.
Understand that I never did bother to try DIY. It just seemed like a whole lot of effort and frustration and like it would require far more patience (and math) than I could muster. I could be totally wrong, and I suspect that others who have actually done it might happily point that out. But, I'm disabled and living on an extremely limited budget. So I just go to Mt Baker Vapor and spend 40 bucks and get 236 ml's of my all day vape, which lasts me about four months - plus they always send a 15ml freebie with larger orders, and I have a ten percent off coupon code. I've not been able to find anything even close to that price. If I'm really broke, I just get a 15ml bottle for 5 bucks to tide me over. And for variety, I enter a lot of juice contests here on ECF.
Anyway I'm not trying to talk you out of it, I just wanted to say it might not be the immediate gratification and money-saving cure you're looking for. Whatever you decide to do, best of luck to you!
I'll speak to a couple of your concerns. Note that I am trying to talk you into or out off anything, just offering my perspective.
Steeping: some flavors need it, some don't. Among the ones that do, you can reduce the time to 4 hours by using something that can keep it around 150 deg F. Searching this subforum for "crock pot" will tell you what you need to know, or you could check out dannyv45's blog for a more concise read.
Keeping notes: When you start mixing flavors into recipes, you will want to do this. If you can be satisfied with single flavor (or unflavored) juice, you could probably fly by the seat of your pants and be OK just by making sure your nic concentration is correct and finding a sweet spot for each flavor. Start low, and then add flavor until you like it. Write down the % you like for each flavor and you are done.
Getting well stocked with PG and/or VG is a bit of an investment, but if you just want to get your toes wet, you can spend less than the price of two bottles of premade juiceand still make 10 bottles of juice.
Patience: You need to be focused for mixing, there is no way around that, but it is not a complex process (unless you want it to be). See remark about steeping above for some details about the waiting.
Math: There are calculator applications that will do the arithmetic for you, but you should understand how the numbers affect your product. A little bit of algebra will go a long way for this.
If you are only spending $10/month on premade, there is very little financial incentive for you to DIY. But there are a lot of people that spend far more on juice, and the chance to make their own for $0.02 to $0.05 per ml could mean significant savings.
Also, I think that DIY-ing is something you should do because you want to. But if you are only doing it because you feel you need to financially, I recommend learning to make and enjoy unflavored juice, It is drop-dead easy and dirt cheap, and many people like it just fine. But again, $10.00/month is not a lot for most people in the US, so if it is not something you want to do, you should not feel compelled.