Custom builds, Alienware etc. with 12GB RAM are not using the RAM for gaming. They are using the RAM for running multiple virtual servers. Or (to quote what I was reading) "doing bracketed HDR exposures in CS4". Or, in your case, rendering. All places I've checked out just now are saying that 12GB is a waste of money if you're doing it for gaming and should stick to 4-6GB. If it's for gaming related purposes, it's basically nothing more than bragging rights which, to most people, will just end up with you looking silly if you don't have a good reason for the additional RAM.
When I say Average Joe, I mean the people who are actually able to afford a PC in the first place, and the ones that intend on using it for gaming - not rendering!
As for "High end" I don't mean "THE BEST!!!", I mean "what you need to run every game out there at the highest settings without any problems whatsoever." I would say what you're referring to is what I used to refer to as a "Specialist Computer" or (as they're referred to at my work) a "CAD PC". Borderline Supercomputer.
Admittedly, I'd
love to try gaming on one, mind you.
Haha. You're lucky that your work requires you have that sort of rig, you'll never have a problem with games - ever.
Not up to date with technology? Dude, it's literally in my job description to be up to date with technology.
I just also stay up to date with what is realistic for the needs and wallets of 99% of the gamer population... it's possible that, being a renderer, you aren't aware of what most people look for in a desktop. Which is understandable.
Anyway, enough rambling.
The point is that normal gamers looking for what is referred to as "mid to high range" (in your words) shouldn't be looking for 16-24GB RAM. That's far beyond their requirements, and will remain that way at the start of 2011, easily. There is no need for them to rush out and spend £5,000+ on a gaming rig. Most people will be looking at closer to £600-1000 if they're serious about their gaming. In the UK, anyway, not sure on the costs of things over the pond.
How much RAM does a PS3 have, btw? I just read it's something like 256MB. Is that true? If so, that's crazy what they can do with such a small amount. Stunned.