I bought the first one, I learned a little bit from the scene, but to me the lack of explanation wasn't giving the vol 1 its full power.
Education in general is not about showing you one case, but explaining you principles that will led you to understand them and "think", adapt for each case.
By showing one case, to me I'll call it observation. Observation + technique + ideas make you do everything we want.
- Observation (+ crits) happen on the forum thank to people sharing their settings.
- Technique comes a little bit from the wiki manual (actually, I understood a lot when translating it).
- Ideas, you get them or not.
The Pro Arch 1 to me was more or less what I can find on this forum, but I was still happy to buy it to support further quality tutorials and also because I can eventually make money from it (so it's fair).
150 is pretty expensive indeed, but it's at least half or one third of a daily rate and if you think big, think about how much daily rates you can sell ones you master quality renders...
However, I think that for this price it has to be more consistant.
I'm conscious that you're not writing a Kray Manual, but if it's dedicated to pros, pros dont't have the same scene to render over and over again, the scene change all the time, and it needs explanation to get the optimal settings for a given scene.
It needs to show different techniques for the same result, and also tips and tricks.
But if it's only scenes like n°1, I won't be able to support it, I might just take a day off and read all the forum

We see great renders on the forum, a lot of people taking their precious time to explain, so it has to be as much valuable if not more...
Still, I thank you for creating material for Kray, it will probably help it to shine.
Peace