The answer here is it really "depends" based on where you fall into the scheme of technology buyers. vRB/ITBM pulls industry-standard costs and, it seems in most cases, attempts to do an average or median on them. These costs are often "good enough" for a lot of folks for getting ballpark figures on cost per utilization. Ultimately, though, if you really want these numbers to be meaningful for you, I almost always see customers altering these based on what they actually paid especially for large-ticket items like VMware ELA/Microsoft EA licensing, storage refreshes, and other hardware or licensing purchases.
Cheers - thanks for taking the time to answer.
I think the tricky thing is that isn't a whole lot of transparency behind the way the reference figures are derived or guidance on how to work out your own figures.
In an era where developers are champing at the bit to utilise cloud based IaaS services (or cut out Infra altogether and go server-less), it is increasingly important to be transparent about on-prem cost - ChargeBack/ITBM are definitely great for doing that, but you definitely need to be on your toes in terms of 'showing your working' to use cost as a factor in the on-prem value proposition.
It sounds like the reference figures are what they are - I'll get my numbers double-checked for sanity and use them where they appear to differ markedly from VMWares.
I don't disagree, just to my knowledge there is no documentation that is published in which VMware state "this is exactly how we arrived at the numbers you get here" and allow you to double-check their math. The reference cost database, which is updated periodically (you'll see this in the Business Management portal if so), is fairly substantial, so good luck in getting precise figures and calculations for the things that pertain to you.