Thanks for the article/link. It would literally hang in the lobby of a a central Detroit office. They agreed to a hard print they would frame. But after my price the line went cold. I really did not want to under cut legitimate photographers making their living. The lowest price suggested from a professional photographer was $250. I balanced that with this 2016 article (https://petapixel.com/2016/02/26/much-photographers-charge-2016/) about selling a single print and the fact that I am a hobbiest and asked threw $150 out there as a price. The emails/texts went cold. But I feel good knowing I did not give away a print. Yes there are lots of stock photos of what they wanted from me. But, for something unique they needed my print.
The article you provided would suggest $50-$75 for an 8×10, (in my case they wanted 2×3 feet), based on time and materials. I still don’t know what the right price would be. But really I don’t care that much. I am not making a living selling prints. However, I think any hobbiest should be prepared if someone asks a price for a print what they should charge. My main concern was not cannibalizing the professional photographers market.