Yeah, I feel these objections, and I don't think your heuristic is bad. I would say, though, and I hold no brief for CFAR, never having donated or attended a workshop, that there is another heuristic possibly worth considering: generally more valuable products are not free. There are many exceptions to this, and it is possible for sellers to counterhack this common heuristic by using higher prices to falsely signal higher quality to consumers. But the heuristic is not worthless, it just has to be applied carefully.