I can promise you that it is cheaper for sure and not a little but way cheaper.
I vape 20 ml's a day after i've begun dripping, and the cost is neglible...
The only thing people mean when they say that they do not really save money on DIY, is that it becomes a big hobby for them, meaning that they always think about new recipes and stuff to blend together and hence orders a bunch of new flavors all the time and that of course adds up, but you do not have to take it that far at all and even if you do, then it about comes out as event up cost wise anyways...
It's important though to look around a little if wanting to save the biggest amounts and buying in bulk for pg and vg, buying 100mg nic in liter bottles and getting flavors at the cheapest places... It's not mandatory though, but it can really shave the cost down to the bare minimum!
As an example e.g.
buy vg and pg, one gallon each with free shipping can often be gotten for very good prices as Essential Depot. Good nic can be gotten from 60 bucks a liter of 100mg and down from e.g. nicotine-river or vape clarity. There's also cheaper ones from e.g. Vapers Tek which is cheap for it's throat-hit version, or e.g. can be gotten from mfs or ecx cheaply(the last three are under 50 bucks each, and vaper tek's throat-hit is 25 bucks right now I believe!). Inawera flavors can be gotten very cheaply in 100ml bottles from e-aromashop.com, allthough it's from poland but who cares if it saves you some bucks...
In the beginning, you can start out small to see if it's for you or not and what you like specifically, and then later on taking advantage of the greater bulk offerings...