What once was Audi's entry-level hatchback is now the brand’s burgeoning small car smorgasbord. From sedan to sportback and diesel to hybrid, the A3 family is about to become an Audi juggernaut. It’s potentially a slippery slope but the German luxury brands have all recently dipped their toes into the realm of the less than very rich. For about $30,000 you can buy a new Audi, BMW or Mercedes, not …