There's a few other GPU renderers out, two of which go for more than $5K per license. I forget what they are (strange names), though some of that was forgetting due to the price tag.

There is one other free option if you really want to play for free, which is Mach Studio Pro. Not sure what happened with it, but it was a very expensive program that went belly up not long ago. You'll have to break out your google-fu to find the legitmate download link, but it's out there to try if you're curious. I didn't bookmark it, but search and you'll find it.

I'll try to remember the other two names. I think one is maxwell (think! that is), and the other is a hybrid CPU+GPU. The web page was red and white if anyone else knows off hand.

Edit: Remembered another, Indigo. 600 euros last I checked, very similar to Lux and has GPU ability but not free

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