I really think its still cheaper, for the majority of components.
I just completed a new computer for about $1200 which was substantially less than a name brand would have charged.
You won't save much, if any, building a lower end system, but you definitely will if you're looking at higher end parts. For example, my local computer store was selling a 12 GB ram kit for $~200, whereas a 12 GB ram upgrade on a Dell XPS 730x is $2100. No thanks Dell.
Or another example, Dell charges $470 for an upgrade from a Core i7 920 to a Core i7 950. This is interesting because the Core i7 950 is only around $560. So does that mean my Core i7 920 is only $90, nope, just price gouging.
I don't think this really qualifies as the "fringe equipment like high spec gaming platforms" you mentioned, since under $2000 is what most places charge for a decent computer that will last a few years.
You mentioned factoring in the time and effort that it will take but this is very subjective. I think a lot of people could assemble a computer over a weekend in around ~10 hours, give or take a few. And if you want to build a computer, this wouldn't even seem like work, at least for me, it's fun!
If you have the ability and desire to make your own computer, I'd recommend doing that. If you don't really know your way around the parts nor want to learn, I'd recommend just biting the bullet and having someone else do it. It all boils down to what you want to do.