Also, as you have discovered, when people find out that a modern world-wide print run is 3 billion cards (not an unreasonable estimate I think), it diminishes how special they feel their collection is and makes them question why they should pay $50 for a Bonfire of the Damned when there are 5 million of them in existence.
You clearly aren't a tournament player. The card is insanely good in standard, and standard is the most played competitive format. If you want to play a good deck, Bonfire is needed for many of them. It's $50 not because it is unique, but because it is good. Being mythic means stores have to open more product to find them, which in turn leads to it's higher price tag.
If I can't get and store store credit, I will NOT play at your store. Simple as that. If you don't allow credit for tourney entry, I'll go to other stores that do first, then come to yours if I have to.
Unfortunately, there is no such thing as strictly better. For each card you listed I can find a niche reason why one is better than another. Although, for your argument you could say: "For all intents and purposes, ______ is strictly better than ______".
You clearly aren't a tournament player. The card is insanely good in standard, and standard is the most played competitive format. If you want to play a good deck, Bonfire is needed for many of them. It's $50 not because it is unique, but because it is good. Being mythic means stores have to open more product to find them, which in turn leads to it's higher price tag.