I would think classical mechanisms of price determination don't really make sense when there's a brand new market: customers don't know how much things "should" cost and businesses can't make decisions via comparison to competitors. So there is some arbitrariness in setting the initial prices - you can't do market research without an established market.
This is especially true with these data brokers, since it's not like "cost of materials and labor + a profit margin" makes sense. In this particular case data is more like a new commodity than a manufactured good.