I think this is a reasonable strategy. It's easier to lower prices than to raise them. This is a relatively novel experiment in publishing and as far as I can tell it's totally boot strapped. I'm happy to pay for this essentially "at cost" to participate in the experiment, but I wouldn't be likely to be taken in by a gold star to subsidize other. I think it's ok to try to grow something like this slowly, to buy time to learn without overexposure.