This is more of an "economies of scale" issue than pricing. The more users adopt oxwall as their platform of choice, the more plugins will be sold. This will eventually push the prices down. Then even the low priced plugins will start generating sizeable income. Which will in turn empower developers to produce more quality plugins at lower prices and attract new users, therefore increasing adoption.
Without this snowball effect, adoption rate of oxwall as a platform will stay at its' current mediocre levels. Speaking of which, when will the platform be modernised? In the next update? Doubtful.
UI is un-intuitive, dated design, horrible mobile version are just a few things on the list that need to be fixed in order to make the platform more attractive.