Basic turrets aren't sold on Freelancer bases anyhow (there's a new one in Koeln by the way) - so you'll unfortunately have to land on a factionalised base that sells them or bug the admins a bit more.:)
By the way, turret zoom and turret steering make gunboats deadlier than they ever were and I imagine basic turrets sholdn't drain your core all that soon on a 75% plant regeneration nerf as well.
