dr_bernie, I think you're forgetting to factor a few things into your comparison. 

If you just choose Lightwave by itself, you're stuck with the native Lightwave render engine.  I believe it's a biased engine, and uses CPU to render.  And this part is subjective, but from what I've seen of Lightwave renders... meh, not very good IMO, at that price level I'd much more likely be shopping for 3ds, C4d, Modo, or Maya.  (honestly, if there was one rendering software out there that I think deserves the 'dying dinosaur' moniker, I would pick Lightwave - just my opinion, not trying to hurt any feelings for any Lightwave lovers out there.  I took a modeling course in which the instructor used Hexagon, Wings, Blender, Carrara, and Lightwave, and watching the videos even though the instructor was in love with Lightwave and praised it to high heaven, all I could think was "thank god I'm not saddled with that piece of..."  I was very underimpressed with Lightwave, but I know it's on of the industry-standard apps, though I can't think why that might be other than force of habit).

Now if someone is content with Lightwave's biased render engine results than that might fit perfectly, but if they are weighing the decision against (theoretical) Carrara + Octane, then it stands to reason they are probably interested in an unbiased render engine, a render engine that can run on GPU, or both.  Lightwave as-is will not fit that bill.

A quick glance on Octane's site shows they do offer a plugin for Lightwave (which demonstrates that there must be a market of Lightwave users who are not satisfied simply with the Lightwave native renderer and instead are willing to pay for Octane), so to get to the same results you have theorized above, you have to pay for Lightwave + Poser Pro 2012 + Octane + Octane plugin for Lightwave + a high-end Nvidia card to run Octane.

So really, apples to apples, it seems to me the Carrara + Octane would be the much less expensive way to get to this result.

Also factor in that most of us discussing this in the Carrara forum already have Carrara and some familiarity with how to use it, so jumping into Lightwave also means devoting hundreds of hours learning how to use a new app (time/frustration cost), and I think it becomes a little more clear why the developers at Octane are willing to spend time/effort developing a plugin for Carrara rather than simply saying 'you Carrara guys should just go buy Lightwave and learn it, and then use our Lightwave plugin'  (not as likely they'd get as many takers from the Carrara userbase).