Who said it was a financial drain? It's a question of what satisfies the requirements of the task at hand.
When I have a task that can use something available commercially, I buy it pre-built. OTOH, when I need something that's not available commercially, I build it myself. Simple. I have no agenda -- I only do what's necessary to get what I want to do the job I have to do.
My point was that adding up the initial acquisition cost of a batch of inexpensive PC hardware, and comparing that price to that of a pre-built high-end Mac that comes with support, etc., is a silly comparison that misses some important factors, that's all.
Why is it silly? That's like saying comparing the cost of any DIY project to the cost of contracting it out is silly.
I don't see anything in your criteria for whether to build or buy that involves any cost consideration. You'll build computer, but only if you can't buy one with the required specs, regardless of how much it costs.
In that environment, Macs are probably great. How many people operate in that environment?