It's important to remember that ships are priced using a component matrix rather than some type of ladder that climbs from one to another. This matrix accounts for many factors including individual component types and rarity. The Nox, for instance, has a number of purpose-built racing components where the Aurora uses more common, mass produced equipment as it is intended both in and out of lore to be a vehicle that introduces new pilots to space travel. While it's true that the Nox does not have a jump engine or a quantum drive of an Aurora, it boasts performance and provides specialization in its intended role that the former cannot match. (For comparison, a purpose-built racing bike can cost significantly more than an entry level car today, despite 'only' having two tires.)