While I haven't yet read the manual (I  intend to do so), I might suggest you consider a 'hobbyist' special pricing first time users kit' (HSPFTUK ;-)

With it comes a couple of things:

1. The requisite handholding I'm sure you're already great at!
2. A smallish (320x240) first render, just to make sure all the textures/objects are correct and non-copyrighted. This smallish render can be repeated up to 3 times so the first time user can learn about the system.
3. A larger 3k rendering which can be repeated once.

So, in total, the newbie gets a possible 5 renderings from this intro kit. They also receive information on how much normally everything would cost as well. It might be a bit of a loss leader, and you might have to disable some stuff like SSS and radiosity, but it would certainly be attractive.

Oh, and one more thing. You might ask the user to submit a 320x240 image WITH the scene file so you know:

1. What it's SUPPOSED to look like and;
2. It CAN be rendered on the users native machine.

Just my 2 cents, Chipp